Untested position players are the hardest guys to place, unless they are at a "name brand" school, ACC, SEC, etc. If he has some numbers from the fall, shoot e-mails to team GM's, make it a positive e-mail giving the info, positions played, and coach contact info. Summer league teams get lots of requests so he should polish his communication a bit. I have received e-mails where a kid didn't tell me his position, or phone number, or even his school name, just basically "I want to play". Anything that might stand out should be mentioned. Your son has a body out of central casting so if he benches 325 lbs and curls 200 lbs, or runs a good 60 yard dash, or has a cannon for an arm, don't be bashful. And while you can help your son draft his e-mail, it should be sent by him. With no track record to speak of, he should play wherever he can this summer as he mainly needs playing time somewhere. When summer league teams recruit, previous good experience in another wooden bat league is significant. Most teams don't carry more than 5 outfielders so if he can play multiple positions, that should be mentioned. While most rosters are full by now, beginning in early May spots start opening due to players bailing out because of grades, injuries, girl friends, etc. Good luck. (I am a team president in the Valley League)
p.s. Some college programs are very active in placing their players, some not so much, some not at all. The major D-1 programs and most D-2's are all active in placing players. D 3's are hit and miss as are JUCO's. Always ask your college coach-he may just wish you luck or he may have connections but it can't hurt to ask.