I think you've thought this through really well, and your thinking is going in the right direction for your goals.
Before we bought a travel trailer and truck, we rented a motorhome a couple of times. Each time was for about 10 days. The first time was in Colorado, and the second time was in Alaska.
You will absolutely learn a ton of relevant RV-living stuff by renting a motorhome. No doubt about it. You'll be able to learn about the plumbing systems (pretty similar in motorhomes and travel trailers), electrical (pretty similar in both), refrigeration (pretty similar). You'll be able to experience what life is like in different types of campgrounds (state parks, national parks, rv resorts, local parks, boondocking - if that's your thing).
The similarities way outweigh the differences between motorhomes and travel trailers.
Do it!!
-Speak
