Things to consider
Rooftop A/C has a heat pump built in so that is 110 volt.If you or spouse is one of those people who cannot survive without A/C then a jenny is needed if you dry camp without hookups. In addition While traveling the rooftop A/C would not be available if you do not have a jenny so depending on how good your dash A/C is it might be a little warm in the unit on very hot days.
The refrigerator may or may not operate on 12 volt but it probably will have a propane gas option. Navion website states 2 way fridge which usually 110 volt or gas. A 12 volt current is required in the gas mode for the units controllers but this is a minimal draw.
If your plan is to stay somewhere for a while without any power hookups (dry camp) then a very small generator or solar charger to keep the batteries full might be worthwhile (not part of M/H). If you are on the move a lot or staying in campgrounds with power then the need for a generator is greatly diminished.
IMO the unit will sell much better if it has a on board generator
None of your stated purposes necessitates the NEED for a jenny now you decide how important the A/C is.