Every child is ready to be responsible for themselves away from home at different ages. You and your child know best what is going to work for both of you.
Who are the chaperones? Are any of them adults your kiddo is comfortable relying on? Are they epi trained regardless of the food he eats?
My kiddo has been fairly independent. She has gone on an 8th grade school trip to Washington DC and on a trip to Florida with my sister. She often goes to amusement parks. She travels on overnights with friends.
Local around town independence was pre middle school. In middle school, she started doing things like movies, eating out, malls, bowling, amusement parks, etc... with friends and without us. She has progressed from there to concerts, etc...
It really depends on if your child is ready to self advocate no only for safe food, but for resolving contact issues, and to have a plan if a reaction should occur.
That being said, if it were my DS2 (who is just 13 and has no allergies), I'd have reservations based on his maturity and behavior and tendency to follow the pack.
Some amusement parks are better than others. One that was out of state (this goes back to middle school) actually said to me, look we are small and we don't have a lot of food options and your daughter's allergies scare us, please, can she bring her own food! Sure! Whatever works out best for all! They gave her a complimentary locker to put her cooler in so she did not have to carry it around.
Hershey was great! Now we did go with her there as we were on our way home from a softball tournament when DD was 12. We prearranged where she could safely eat for both lunch and dinner. The staff were fantastic! We had a great day at the park!