MAKE SURE YOUR PROPANE TANKS ARE OFF AND BLEED LINE FROM STOVE TOP BURNER.
I found a wrench and adjustable pliers work well to remove gas line. The line is malleable so moving it out of the way is fairly easy.
The air supply hoses are removed with a 1/4 turn off, no need to mess with clamps. you can mark them if you think you need to. there will be a couple of screws holding the furnace to a wooden base, remove them and pull unit into coach onto a blanket or something to protect floor.
You basically have to remove fan assembly, surprisingly simple. once its removed the sail switch is inside the fan cage, mine had a few screws that needed to be removed and it splits in half.
In the link is the sail switch you need, two screws two wires. Always take pictures as you remove wires etc. so you know where they all go when reassembling. I was nervous at first but it's not that bad. Did I mention taking pictures? LOL
When I changed mine last year I added male / female spade connectors to the thermostat leads for future maintenance.
Once re-installed, attach gas line and make sure the YELLOW teflon tape for gas appliances is used. Soapy water in a squirt bottle to test for a solid connection works well. Make sure there are no leaks and test it a few times once the furnace is operating.
This of course is assuming you have the tools and are somewhat handy.
If you feel this is above your skill set, get a "professional" to do the work.