You will not really know until you have the TT, have some camping experience to determine your power requirements, what you need to be comfortable in the places and times you choose to camp.
If your RV is 30 amp service, 3600 watts continuous capacity (available from a 4KW genset or a coupled pair of 2000 watt inverter units) will provide as much power as you can get plugged into the grid. This will still not be enough if the air conditioner tries to start while your daughter is using her 1600 watt blow dryer on high and has her curling iron plugged in. But this will also trip the main breaker in your RV or the breaker on the generator or service pedestal, whichever heats up fastest for thermal loads.
If you never run air conditioning, don't use toasters, electric griddles or frying pans, or high wattage grooming appliances, a single 2KW genset (typically 1600 watts continuous) can work to keep house batteries charged during "generator hours" for storing enough energy to get you to the next charging period on your 12-volt loads.
It is a lifestyle issue. I used to get through a three day camping weekend on a pair of carbon-zinc D-cells (never used the spare set I carried) but now in my RV 1200 KWH might not get me through a cold winter's night, and come morning with the wife fixing breakfast and the daughters grooming hair, 3.6 KW might not be enough power to get me through the next 10 minutes. Considering that I live in a 60 year old house with only 7.2 KW service, same issues come up at home.
Power needs depend on lifestyle choices, not which RV your bought.