[JRTJH]

Upgrading from a 1500 to a 2500 will give you "increased towing capacity" but depending on the trim level of your 2500, it may not give you the payload (especially in a diesel) to tow the trailers on your short list. One of them has a GVW of 10K the other a GVW of 11K. You can expect a pin weight around 20% for most fifth wheels, then add the weight of the fifth wheel hitch (a sliding hitch can weigh upwards of 250 pounds, so with an 11K GVW trailer, sitting in your short bed truck, you can plan on potentially having around 2500 pounds of "payload from the trailer and hitch"... Then add passengers, other cargo and you can quickly overload a 3/4 ton diesel truck....

If you're looking at a fifth wheel, I'd urge you to get a 1 ton tow vehicle, especially if you're considering diesel power. The cost difference between a 2500 and a 3500 is "negligible" (usually around $500), the ride is almost identical and the payload can be anywhere from 1000 to 2000 pounds greater (again, depending on trim level)....

There's significantly more to towing any trailer than "GCWR" or "Max Trailer Weight" in an advertising brochure.