Class A with four 3 point seat belts (ie, shoulder straps)

My Winnebago C has:
Two facing front in the cab.
Two facing front in the dinette.
Two facing sideways on the fold out sofa.
One facing backwards on the other side of the dinette.

I think you should NOT concentrate on counting seat belts in your initial shopping. I suspect that belts can be added to a LOT of models easily and fairly inexpensively.