Are you shopping for a front or rear engine coach?
With a pusher, where the straight 6 and transmission are both behind the rear axle, your overhang mostly predetermined. Then, to get reasonable weight on the front axle, it is “pulled back". Thus the relatively short wheelbases on pushers under 35’ long (actually most under 40’ have less than ideal length/wheelbase ratios). E.g. Tiffin RED 33A: 35’ length/198” WB = .47 ratio.
On a front engine RV (gas or diesel), the engine can sit directly over the front axle and the rear axle can be placed where balance is best (drive shaft can be made to whatever length is needed). Thus, you find better length/WB ratios. E.g. Tiffin Allegro 31: 33’ length/228” WB = .57 ratio.
That brings the question of which gives a better overall ride and control - a leaf spring front engine chassis with a good wheelbase ratio or an airbag pusher chassis with a short wheelbase? I’m all ears.