I agree, even a 3 yr old can be helpful with a little coaching. Kids generally like to help, especially if they know there is fun at the end.
Maybe a food checklist would help. Stick with basically the same menu and keep a list of items needed to prep. Non-perishables should stay in the trailer and be inventoried at the end of the trip, and replaced ASAP. Perishables can be checked and replenished a couple of days before the trip.
Seriously half the battle of food prep is deciding what to cook and getting the ingredients together to cook it. If those things become a non-decision and a routine, it's much easier.
Your key on all of this is to leave as much in the trailer as possible and anything that is removed, such as towels for laundry, goes back to a central location (like a big laundry basket or tote) so it can be easily taken back.
Non-perishable foods go back in this spot to take back to the trailer as soon as they are purchased.
Let kids (at least the older ones) pack their own entertainment and electronics. And possibly get some things that stay in the trailer, such as outdoor games or board games for a rainy day.