Newbie TT Buyer needing off grid power for 1 week

I'm finally buying my first new TT and am running into one major issue -- no budget priced entry level trailer (15K) has an on board generator.

I plan on using my Trailer off grid so I need a way to crank up the AC all day day long and then at night just run bats or the generator sparingly. All of my past RV's have been class C that had onboard genny's so they just drew gasoline and would do OK as long as I filled the tank just before going off grid.

Any suggestions on what I should do to or is there a RV company that makes units with optional generator?

Thanks in advance for any insight.