J.K.
My daughter will be 3 in September and still sleeps in her crib. We recently spent several days with my brother-in-law and she slept on an aerobed, with her older sister in the room. She did great. When she came home, she went back in the crib without issue. We are going to the beach in a few weeks and plan on the same sleep situation.
I would keep him in the crib, if he likes it. You might want to show him what he will be sleeping on when you are away, so that he knows what to expect when you get there.
Good Luck.
Jen