So that is a pretty decent sized 3 phase converter. It will do an ok job of recharging deeply discharged batteries and get them up past 60 or 70% charged pretty quickly. I have the same one and it's a bit slow getting the rest of the way charged but I bet it will work fine to get started. When you have full hookups it will top off the batteries as they need.
So the question will be do you have enough battery to do what you want each evening without hookups. Then it comes down to the particular CPAP machine and TV. You just might have enough already in the RV.
Jim