I know I am late to this OP about "How many actual scouts at PG events", but I wanted to chime in to hopefully help other people...
My son would email numerous programs (Head Coach, Hitting Coach & Position Coach), and let them know when & where he was playing in big PG Tourneys (and other big tourneys), and of course, why he felt he was a good fit for their program if they were looking for an "xyz" player, etc.
Some times, he would not hear back from said coaches, BUT very often one some of these coaches would be at the entire game watching him before they contacted him. The old saying of "You never know who is watching you play, warm up, how you handle an error or a strike out" is very true IMO.
I'm sure many on this board will attest, there are numerous stories of where a scout came to a game to watch some stud pitcher or SS and someone else showed out...
* Again, player needs to reach out to programs and coaches in advance that he is even remotely interested in to LEVERAGE these tourney games and opportunities.
Best of luck!