Camping with 10 month old grandson - dining solution?

You're way over-thinking this. All 3 of my kids started camping at age 4 weeks. We held them in our lap to feed, or used a small foldup highchair outside. They all survived fine.

And only 3 adults and 2 kids in a 27' trailer with slideout, and you have to sleep in a tent? No way. That trailer must have at least 2 beds, if not 3 (fixed bed, couch, dinette). Worst case, a blow up mattress on the floor adds sleeping space.