This may sound like heresy to Transit fans, but it seems to me that one solution could be to switch these smaller, lighter, narrower, and lower-profile B+ gas rigs to Ford Econoline chassis with SRW and similar 158” wheelbase.
With TPMS, single rear wheels shouldn’t be as big a concern, which is partly why we now see many large 5ers being pulled by SRW pickups.
A similar-size (to Coachmen) compact B+ on Econoline with 6.2L truck V8 might only get 11 MPG instead of 12 MPG on Transit with 3.7L gas V6 (I’m excluding diesels), and it may not drive as smoothly, but I think it would be a lot more rugged and the cab more RV friendly. Towing capacity might be a lot higher also.
Granted, the SRW Econoline Cutaway chassis is only available with 40-gallon fuel tank, but at 11 MPG the range would be identical to larger Class Cs that get 8 MPG with 55-gallon tank.
It’s unfortunate that since the Firestone tire debacle, we’ve had minimal interest in SRW RVs in US. The Thor 19G Class C was one of the last I recall, and that was only ~ 20-ft and on 138” WB chassis. A slightly larger version, like Coachmen T24RB above, may go over even better.
By the way, thanks for all comments.