As I always tell the kids, you are never to old to go to camp.
I am 41 and still work at camps. Although I'm taking this summer off. A lot of camps still have older staff. You might want to ask this question when you are interviewing. You might not be able to be in a cabin (ACA has a new regulation for that ). or the Camp might have a rule on that but you can still work at camp somehow.
A lot of private camps have older adult staff. Try Camp Lohikan in PA , they have a wide range age of staff on their camp. It's a great camp, I worked there for two summers.
They also have some sister camps too.
Again private camps are known to have more older staff.