I agree with the others. Add a battery and a few LEDs in the lights you are most likely to use and you should be fine for a few days. We can make it a weekend on a single grp 27 battery including running the furnace at night in freezing temps.
A bit of solar would make it so that you could stay out longer, dry camping/boondocking is addictive after all. You could pick up 120w in a panel along with the wires and controller for less than you think if you buy them separately. Left portable they can be set in the sun while the trailer is in the shade, mounted will mean your battery will be charged and ready to go whenever you are. We spent $200 thru craigslist and ebay on the solar we take with us.