Is this really how you go about selecting which motorhome to buy, it's gotta have a gasoline engine, or it's gotta have a diesel engine?
My experience is that the majority of RVers make the transition from gasoline to diesel at the time when size, weight, features, performance, and budget warrants it.
There's no new Class A motorhomes which have the features you want, that come with either a gasoline engine or a diesel engine. I'm referring to the same model and size of motorhome except for the engine. I can easily understand the reasons why diesel vs gasoline options are not offerred for the same motorhome.
The discussion of gasoline vs diesel engines IMO is a discussion on engines, not motorhomes.
I've got nothing against gasoline engines, other than they're not appropriate for the motorhomes that I like, or would buy. But, they sure work good in my cars.