Nothing wron with 4x T105. Seems like a bit much. A spare G27 is probably fine.
What you have not addressed is the charging system. You need a good three stage converter to quickly charge those batteries. The generator just needs to be large enough for the converter. 1000w gen is good for 35 amps and 2000 watt is good for 70 amps into the battery.
For inside a campground with probably other tent campers I really recommend a low noise Honda or Yamaha. 1000 or 2000 is your choice. 2000 should also run the microwave if needed.
Lights and furnace are generally the largest draw on the battery. Unless you have LED lamps then you are good to go. Bring extra blankets to keep the furnace off as much as possible. Or maybe you will not use it at all.
So for now focus on what your converter is and what you need for charging.