Deviled eggs are a hit. Make sure and use 1-2 Tbls. butter whipped into your filling recipe. This helps "set" the filling when it is refrigerated and assures that your eggs arrive without any unfortunate "filling" incidents from RV travel.
Bring along some fresh dill or thyme and sprinkle on top when you arrive. Fresh herbs really help bring a pop of flavor.
Bed, Bath and Beyond or Amazon have AWESOME rectangular, stackable eggs keepers (2 dzn) that fit into a small TC fridge like a dream!
Fresh guacamole (do all the prep/chopping at home - just mix when you get there) also tastes great. Make sure to bring a potato masher to mash the avocado.
And, lastly, wine/beer :) No one would ever complain about that.