Well you use the generator to recharge the chair so we won't include that
Yoru two Interstate U-2200's or equal are what you need for the RV overnight.
That leaves the Concentrator.. NOTE> have a bottle on hand just in cuss.
4 amp at 125 volt is 40 at 12.5 so we will go with 40*25, why 25, simplifies the math. 1000 amp hours per day. or about half that overnight (Generator hours to generator hours) since you can only use half your battery capacity (Assumes DEEP CYCLE) we are back to 1000 amp hours
4 pair of GC-2 would likely do the job. with a bit of assist from teh existing pair.. THe downside. that's gonna make a BIG dent in the cargo carrying capacity for that RV. You might do better to use bottled O2 when traveling. Use the concentrator only when generating