@Justlittleoldme,
I really feel like you should sit down with him before this trip happens (sooner the better) and give him the scoop on how you feel. You appreciate the gesture and thought behind the trip, the idea of hanging out and doing stuff sounds like fun, but you aren't feeling a romantic connection with him. Try to avoid sounding confused about your feelings or it leaves him with the idea that he just needs to try harder to make you love him. Be firm and concise about how you feel with no room for interpretation. You enjoy his friendship, but no romantic interest and no desire to continue the relationship as a romantic one.
In short, you need to friend zone him and make sure he gets it.
And please don't feel guilty. He's a big boy and should be able to respect how you feel and seek other dating opportunities.