My biggest worry as a father is someone 3 or 4 times his age playing weekend warrior and getting extreme with him.
No need to worry about that. We regulate our own. If necessary, we eat our own too. No one gets out of pocket, and if they do, they don't remain out of pocket long...or they simply don't remain.
Your son will be in good company.
Regarding a field, you may have to drive a good ways away to get to a field. There's one in McCordsville that WilliamC runs, Amazonwoman and her husband run a super nice field near Seymour and then there's another couple of fields south of Indy (Spec Ops and Battlegrounds). Past those, there's Blast Camp and Sherwood Forest up north, but those are at least an hour or more drive away.