Roadtreks: Easily Modified?

[ExpressVan]

Our 27 year old conversion van, modified for camping, will need to be replaced in the next fews years, after 15 years of great service. I've always liked older Roadtreks, but am not sure I can make one work for us.

Specificially:

My husband is 6'2", and we really need a full-length bed. Ideally, we would like to use the full-size mattress from our old van and leave the bed made up all the time. Could that be done in lieu of the convertible beds?

The driver's seat in our Chevy Express needs to be racked back quite a bit for his driving comfort. It looks like many Roadtrek and other Class B's have something directly behind the seat that would prevent that. Could some of these items be removed?

Is there space under the sink for Jerry can-style gray water containment as an alternative to using the built-in tank?

Would replacing the 3-way refrigerator with a 12-volt compressor unit be feasible if desired?

How difficult is it to replace a Kool-Cat heat pump unit with a window air conditioner? (Would an RV shop be willing to do this?)

Is there enough storage space (perhaps under the bed if the sofa is removed) for a small CLAM (43" long; 8" tall bagged), two camp chairs, a 27" roll up aluminum table, a Coleman stove, and a 5 lb. propane tank?

Any information or suggestions is appreciated!