Welcome to the forum
Generator size will depend on what your trying to accomplish. Charge the battery(s) only a 1000W would do the job. Charge the battery and watch TV While microwaving something maybe the 1000W or step up to 2000W. General accepted rule us 3500W or better for the AC.
You can get a single gen rated for 3500-4000 watts, but they can be a bit heavy. You can get a pair of 2000W gens that can be “tethered” together for about 3600W. That way they are easier to carry/lift and you can run 1 if your not using the AC.
Either way, I would definitely get an “inverter” gen, as the power supplied is more constant and “cleaner” meaning it won’t damage your electronics.
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2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.