I wonder why the 22M has larger black and gray tanks than all of the other Winnie Minnie models except for the just the gray tank on the 31G?? Strange. It's too bad you have to put up with a slide on the 22M to get those great drycamping tank sizes.
Unfortunately Winnie doesn't offer a Ford E350/E450 based non-slide 24V floorplan anymore. Our E450 24V has large tanks and a lounge chair. With only the two of us and one small pet-person we don't need a couch for any reason, but the swiveling and extending lounge chair sure is great. Our dinette will of course quickly convert into a full size bed for an occasional adult or two guest overnighters.
One thing Winnebago doesn't include anywhere on their website (as well as no other Class C manufacturer, as far as I can tell) is whether or not their models are of a basement design. A basement design means you have taller outside storage cabinets, but also requires a step up onto the coach floor from the cab floor. This step up also means that the addition of a cab swivel passenger seat doesn't make much sense because you're sitting too low in it - your legs stick too much straight out and it would be impossible to get directly up out of it onto the coach floor. Hence with a basement design, the coach pretty much has to have a lounge chair or two somewhere in it for relaxing in the evenings.
Another feature Winnebago and other manufacturers don't mention about their coach designs is - is the area under their dinette seats entirely available for storage or are there appliances under them (furnace and/or water heater) taking up some of this potentially large storage space? Our E450 24V dinette has all of it's underseat area available and conveniently accessible - this is a huge plus for interior storage.