Rovinred, we jumped off in to it without renting first.......I don't think anybody rents 5th wheels. We did do a lot of research and read as much as we could on all these RV forums. We also attended several RV Shows and asked other owners a lot of questions as well as the sales people. Generally speaking....we quickly learned that we could rely on information from other owners a lot more than we could from sales people.
There's a big difference in all types of RVs. For instance, a class A and a class C. The class A is going to have a lot more storage. Similar difference between a trailer and a 5th wheel. But yet with a trailer, you still have the pick-up that you can keep stuff stored in, if you have a shell on it. We have a 5th wheel and I have the large tool box back there that actually holds quite a bit. I keep other stuff (folding table, 2x6 planks for leveling, generator, gas can for generator, etc.) back there around the 5th wheel and still have all the storage space under the front of the trailer.
There's just a lot to learn. Some mfgs. (or sales people) will refer to a unit as being an all seasons trailer but there's a lot more to an all seasons trailer besides just heated holding tanks. A true all seasons trailer will have heavier insulation, thermal pane windows, the plumbing will be ran through heated space under the floor, etc.
I'm pretty smart and I thought I could look at a unit and tell quality. In some cases that may hold true however, RV mfgs. have a way of making a marginal unit look very, very nice. Fortunately, for us, we learned about RV Consumer before we pulled the trigger. RV Consumer is like the Consumer Reports for the RV industry.....they don't accept any advertising and are totally self supported from it's members. They evaluate and judge every make, model and year of every type of RV. They evaluate the quality, reliability, overall satisfaction, value and wether it's a weekender, vacationer, snow birder or full timer. It's a bit pricey to join but much cheaper than making a huge mistake by buying the wrong rig.
I hope some of this helps you in considering and thinking about some things that you might not otherwise have thought of.
JC