That motorhome does look nice inside and would probably be fairly easy to make livable. Do you notice the waves in the sides of the motorhome exterior? It looks like the structural parts, wood, are partially gone. I think you'll be spending a lot of money fixing up a motorhome if you decide to go that way. I'm guessing that over your three year plan you'll spend a couple thousand keeping your motorhome dry and livable.
How about you take the money you would spend on that motorhome and get yourself a bus. The weather is just going to keep getting better so you've got all summer to get the bus insulated before winter gets here. It cuts three years out of your plan too.
You're buying mobile lodging either way, which to me means you're going to want to go places. Right now that fuel tank would be about $250 for a fill. Old motorhomes frequently have a lot of problems on a trip mostly from not being driven.
I just don't think the motorhome is worth it to slowly strip the usable parts for the bus conversion. Many people end up buying the tanks and things so they fit the bus well rather than trying to adapt motorhome parts. A free motorhome is a different story, and there seem to be free motorhomes just about everywhere.
Honestly it is uncomfortable living in a bus while converting it, because that's what I've done over the past 18 months. It's working out and because I live in the bus I'm often looking at how to take the next step in fixing up the bus. Sorry, I mean "van."