Just got into the Class C thing after doing 5er for years. Got solar which is useless in forested camp sites. No generator (yet?)
Thing is, Class Cs have the magic of alternator charging AND you can use the smaller ones (our 28 is as big as you can go for this IMO) to also drive around in like we used to with the truck while leaving the 5er on site.
All that driving around in the truck did nothing for the 5er, but it does replace some AH in the Class C. Plus you are not then under the trees either, so you get some solar if the weatherman permits.
The other thing is to carry more batteries. Once again it is all about scenarios. You need about a battery per day off- grid, so if you want to stay five days and you only have two batts, you need to make up the diff of three batts by recharging. BUT--if you have four batts, now you only need to make up one batt's worth over the five days. Now you can apply a little alternator charging and any solar and get it done.
Say you get 20 amps (a modest amount) then in one hour of driving around each day for five, that's 100AH --ie the size of one battery.
If you are short two batteries with only two in the RV and your stay is four days, now you can still manage, but have to drive around two hours a day, or be getting 40 amps from the alternator, so you can do it with still the one hour a day driving. (You can also just idle for a while)
We are still learning how to do all this kind of thing with the Class C, but it is not like the 5er at all. Also you can just move to the campground parking lot during the day and get some solar time, while still being in the park. Go back to your site for supper and back to the parking lot after breakfast. Whatever.
Might still need a generator depending on scenario, but a Class C means you have some interesting options not available with a trailer.