The DW and I can usually make 2 1/2 days on the battery then the water pump cannot draw enough power to shut itself off. As suggested I just took a set of jumpers and ran the TV for 15 to 25 minutes to recharge the battery. Now I just bring a second battery and switch it out.
The DW is getting to like the boon docking experience because it opens up more camping spaces in the MI and WI, especially in the UP.
Cell phone and TV reception were nonexistent on our recent trip, so except for my whining about no microwave, there is not much difference without electricity. My frig and water heater switch to LP. The furnace will draw down the battery rather quickly but we rarely have needed it.
So give it a try, three or four days should give you a good feel for boon docking. We were very fortunate because there were very few mosquito when we were up there so it was quite pleasant until dusk.
I suspect the phantom loads will be you biggest draw.