If he is your best friend you should be reasonably comfortable describing your feelings. Don't hold back just because those feelings are about him and you are unsure about how he feels in return. Revealing emotions always involves risk of rejection on some level.
You're probably getting ahead of yourself with this idea of a long-distance relationship not even knowing if he likes you back now. However, long-distance relationships are difficult to maintain even for people who are madly in love. How about agreeing instead to a "special friendship" and making sure to connect via FaceTime, social media and even snail mail? Make sure you establish upfront that you can date other people but reconnect at summer camp (or other times) in the future. If the relationship blossoms you can make future plans to be closer together geographically (attending college, etc.)