I have on several occasions, slipped a board under the tires of the trailer to keep it level when hitched to the truck and gone inside to shop or go to a restaurant while traveling. Just like at your camp site, find the spot where you'll stop. Lay your board (or Lynx Lego block) beside your tires, go backward just far enough to get the blocks or wood in front of the tires, and then pull forward onto the block. It's so simple to do, takes only a moment, and can keep the ice cream frozen like ice cream should be and not turn into ice milk if I'm delayed longer than expected. I do this all the time when traveling in uneven parking lots. No one has every said a word to me about it being wrong either.
