You got a lot of good detailed advice so far. But to answer your question directly you will not have a problem dry camping for a 3 day week end. You don't need a generator even with one battery probably 110 AH. I have 232 AH and at the end of 7 days the batteries at only discharged 50% and I shower in the MH. Also you will be camping so use lanterns either gas or battery around the camp site and inside the trailer at night. Even with your small tank size you will be fine but a good practice with small tanks and no where to dump is to bring a 5 gal container with you that has a spigot on the bottom that you can put on the out door table to wash your hands get water for cooking etc and just refill when need and dispose of the waste water like the tent campers do. Have fun you will be fine.