I have 4 group 24 deep cycle batteries, a Boily 3600 generator, and a 3000 watt pure sine wave inverter from E-Bay. I have a remote power switch and a 50 foot extention cord plugged to the inverter that are stored in my laundry chute in the inside steps. I can selectively power any 110 Volt AC device, or plug in to the trailer's main power cord (and turn off the breaker for the battery charger/convertor) and power the whole trailer with the inverter.
I have been using this system a lot the past few days as I am sitting in a quiet COE campground and want to minimize my generator use. I can watch TV, which came in handy in the howling wind and rainstorm we had last night, without going outside to start up the generator. I run the generator in 1 1/2 hour stints to recharge the battery bank. I monitor the 12 volts DC with a plug-in voltage monitor available at RVing stores (I previously installed a couple of 12 volt DC outlets in the trailer).
If I had this to do over again, I think I would just have a 2000 Watt Honda generator. That is smaller, lighter, and quieter than the Boily. If I need Air conditioning, I would go to a park with hookups.