Voylyn,
Putting the truck debate aside, I'll try to answer your question as I think I understand what you were really intending to ask. Yes, you got lots of truck / payload responses, so putting that aside, assume you have the appropriate tow vehicle for both.... OK?
We went from a 35 foot Keystone Outback to a 41 Foot Montana High Country. The Outback was a travel trailer and the Montana is a Fifth Wheel (same size as the one you are considering.)
Our Outback had 3 slides (2 opposing in the rear living room and a closet slide in the front bed room). The Montana has 4 slides (2 opposing in the front living room with front full window), the main kitchen slide (middle section), and the rear bedroom. Bed is in the slide.
We towed the Outback with the truck in my signature below. I used a 4 point Equal-i-zer weight distribution hitch system. The total length of truck and trailer hitched was 57 feet.
We now tow the Montana (same truck) using a Demco fifth wheel hitch in the bed of the truck. My truck is a long bed, the hitch is directly above the rear axle. The total length of my truck and trailer hitched is now 58.5 feet.
Even though the trailer is 6 feet longer, the overall towing length is only 1.5 feet longer. So, as far as length, you will not experience much differenct.
The difference will be when you make turns. The Montana has a longer tail swing than the travel trailer. The wheel base is different between the two (That is the difference between the hitch ball to the pivot point on the trailer axles, or the King Pin on the fifth wheel hitch to the pivot point on the trailer axles.
The wheel base (from my experience) is shorter for the fifth wheel, or at least it seems like it is. The pivot on the fifth wheel hitch is in the middle of the truck bed. The trailer pivot on the ball is behind the entire vehicle. This change in pivot points makes driving the two a different experience. DO NOT MISSUNDERSTAND ME HERE ..... I did not say either one was "BAD". I said they were different.
Coming from 64 years of towing nothing but bumper pull trailers, and then getting and towing my first ever fifth wheel took a 2 year learning curve before I realized one day, I was driving and NOT thinking about the fifth wheel behind me. It took 2 years to finally figure out how to back up (consistently) into a 90 degree angled parking spot (like a campsite). It took 2 years to finally REALLY figure out how much tail swing the fifth wheel "really" required ... and after clipping the end of the trailer, not once ... but twice.
Again, neither one was "better" than the other. They are both just "different" and the learning curve, adjusting from a bumper pull travel trailer to a fifth wheel trailer may take you also a learning curve. You may find it very easy and catch on right away. Or you may struggle with it for a long time. We each learn and get comfortable with these things at different rates. The important thing for you to do when you get the new Montana is to practice, practice, and practice backing, turning, and tracking that tail swing. This is best done in empty parking lots. But, the good thing is ... there will come a point when you finally have the "AH - HA!" moment. In other words, you'll have that decisive moment when all of a sudden you realize ... "I get it!" Just be patient. "It" will come.
As far as length, you'll not notice any difference towing on the highway, passing vehicles or being passed. You'll notice the difference when making turns in town... only because of that tail swing. Also, the way the fifth wheel WILL track different than your bumper pull trailer. So turns in town will require a different wide turn. That's why the empty parking lot training is so very, very important when you first switch over to a fifth wheel.
For me, it's now been over 4 years. Now, it's really comfortable. I'm not skeptical about pulling anywhere. And yes, I've maneuvered my behemoth in some really tight places, gas stations, and campgrounds and campsites that seem impossible initially.
Now ... if you have endured through my very long post ... a word about your heat.
Your Montana has a very high ceiling and it has 4 slides. The shear size of the interior daunting when it comes to heat. Your Montana will also have a heated underbelly. That means the space between the bottom of the trailer and the floor you walk on is heated also. There are open ducts running under the floor of your Montana that blow from the furnace to keep pipes and tanks from freezing. I am not exaggerating when I say, 50% of your heat will go into the coach where you live, and the other 50% will blow into the underbelly.
And when the outside temperature reaches about 30 degrees, you'll run through a 30 pound propane tank in about 5 days. At 20, you'll run through a 30 pound tank in less than 3 days. At zero, you'll be running through a 30 pound tank about every 2 days (or less). At zero, the furnace will never turn off. BUT! It will keep the trailer warm and the pipes won't freeze. THAT is the trade-off.
When temps get that low, it is important that the furnace keep running if you want the pipes to keep from freezing.
If temps are above 40-45 degrees, you can use your electric heat pump (on the air conditioner). Below 40-45 degrees and heat pumps don't work. They blow only cold air then. You will also have an electric fire place. These spit out a lot of heat. Again, if temps are above 32 outside, the electric heat is the way to go. Once temps reach below 32, you absolutely need to keep the furnace running.
We have found (when temps are in the 20's) the furnace fire place, set on 74 with the electric fire place, and 2 ceramic space heaters positioned in key locations will work well to keep heat blowing under the floor and will keep the coach warm. The secret is to find that balance where the electric supplements the gas furnace just enough to keep the basement heated, but not shut down because the thermostat on the wall thinks it's warmer than it really is. This takes some time to figure out, and no doubt you'll run through several tanks of propane before you figure out that perfect balance. But, again, once you figure it out, supplemental electric heat is the way to go.
I know you will enjoy your Montana once you get it. And I totally understand your concerns moving from a travel trailer to a fifth wheel. ... really!
You might also check out the
Montana Owners Club forum too. It is also sponsored by RV Life Pro, just like this site is.
If you do, be prepared to get blasted about that 1 ton truck there too! It seems that topic is just the nature of the beast when it comes to towing Montana's!