The job which you need to do first is: Estimating your power usage.
If your 'Boondock' trips will sometimes involve the Air Conditioner, then this is the minimum Generator to run it, and the most-respected Generator of it's size: https://www.amazon.com/Honda-2200-Wa...dp/B07R1HK2RL/
. (Per this post: http://www.airforums.com/forums/f295...ml#post1942372
It includes Receptacles for both 15/20A (a NEMA "5-20R T-slot") and 30A (a NEMA L530P "twist lock").
You will want this adapter, to connect the straight-pinned RV plug.
. You need the '30A 3 prong Generator Version', which converts provides an L5-30 Plug on one side, and a TT-30R Receptacle on the other side.
- - - -
If you WILL NOT need air conditioning, then you have a number of other options. (Solar Panels, or a smaller generator, or charging from the Tow Vehicle with something like this: https://www.renogy.com/renogy-12v-dc-to-dc-on-board-battery-charger/)
But it all starts with the question: How much power do you really need?