If you can get in contact with them before the camp so that they know who he is before he takes the field then go for it. But don't expect to just show up at the camp and have them notice him.
I've never been to a third party camp, but from talking to college coaches they go in with a list of players they have heard of or that have expressed interest and then pay close attention to anybody who stands out (velo, speed, big bat, etc). Way too hard to keep tabs on 90 players and evaluate each. Three sessions is a long day. The coaches lose interest after a while too. If nothing catches their eye they're often just going thru the motions as well. Don't forget, more kids don't belong than do belong at these camps.
Use whatever resources you can to get in contact with the coaches. A summer coach/trainer with connections will help here