Diesel pushers seldom have a long rear overhang, so their wheelbase ratio is seldom a concern.
However, a longer wheelbase in proportion to the length of the RV is a good thing.
The formula for the wheel base ratio is Wheel Base in inches, divided by the overall length of the coach in inches. The higher the percentage, the better.
The long rear overhang is more of a problem for gas powered coaches when making turns because the rear swings out and can strike something unexpectedly. Inexperienced drivers are usually unaware of and too often have accidents because of it.