The largest power usage on a typical boondocking TT will be the furnace fan in the winter time. The pump doesn't use much power because you aren't using it that much. Obviously, I'm not including things like AC, television, microwave, etc. I can go two days with the furnace running most of the night, on one deep cycle battery. In the summer, I run a Yamaha 1000 watt generator to run my AC for about 6-7 hours which also charges the batteries and lets me charge phones, watch telvision etc. if I want to. If I didn't need the AC or the furnace, I could easily get by with two batteries for close to a week without any issues. Keep in mind, all of my lights are LEDs.
The biggest learning curve that I had was that I need a shower tent and outside shower water heater (like a Camp Chef) and then all will be great. This way I won't fill the gray water tank and I don't need to shower in the cramped wet bath. We were able to get by for over two weeks this summer, but 3 days had power in a campground and many days were were pulling the trailer. I never refilled the 80 gallons of water over these two weeks and I never filled up the black water tank. I did dump it once in the middle of the trip and once near the end.