Good plan to buy the motorhome, live in it, see what you like, don't like, what you need and don't need. And then you'll know what to do for the 2nd one. You can either rebuild the motorhome, or build another one.
I have a 1974 Dodge motorhome, and almost nothing in it would be useful, mostly because its old and all based on propane (fridge, stove, heater, water heater) and the toilet and shower use black tank, the sink is too small. I want an all-electric rig, but if you want to use propane it would be more useful.
It does have the dinette, and some awesome rollup upper cabinets.
Newer motorhomes may be a lot better.
And then completely strip it down and start from scratch...like you would be doing with a worn out School Bus. Or sell it if you don't like how it drives and get a school bus if you like leaky windows and less height and width.
It is a major effort to build a motorhome from scratch and will take...well for some many years.