A harness is a series of straps that attach to a leash that will keep them from flying away if the get spooked and you are holding the leash. Here is a link for the company I go through.
http://www.fredbird.net/BB - A flight suit has a leash component, lanyard style that would not allow the bird much past your shoulder.
Either way you decide to go, order it now and start working with it. Your bird may not accept a harness or flight suit, keep that in mind.
Remember that any mosquito repelling products you may use camping will be toxic to your bird, so make sure that you wash well before touching him or his items. Make sure to have the phone number of emergency vets in the area you will be camping at so if the unthinkable happens you know who to call.
I'm glad to hear that he will be in an RV, tent camping with a bird is just too dangerous! Remember to lock the door when you put him in the harness or flight suit so he doesn't escape when someone comes inside and he isn't leashed up yet.