Both my 2012 (D1 player) and my 2016 (soon to commit to a D3) were in the full time program at IMG once upon a time. My 2012 was also very young for his grade (13 year old as a hs freshman) so the PG year was something we pursued purely for age/maturity as he was gifted academically and athletically.
I highly recommend not doing IMG for a variety of reasons including cost. I've posted many times on this topic.
We looked at a lot of post grad programs throughout the US. www.boardingschoolreview.com was a starting point for us. Visited a number of schools. The best academic schools adhere to the traditional timing for their sports, i.e., baseball is a Spring sport only and typically doesn't start until March at the earliest due to the weather. This timeframe is after college baseball recruiting is done for most schools. That means a PG player will have applied to colleges and be committed to play college ball before he sees the field the Spring of his PG year.
As I think has been noted above, the Summer between Senior and PG years is the most critical for college baseball recruiting. If a player has not already committed, getting exposure via showcases and camps is most critical at this time.
If I had to do it over again, and I wish I could, my 2012 would not have done a PG at IMG as academically, he didn't need it. He would've done a "gap year" that we created with the following: taken some junior college classes (though not enough to impact collegiate eligibility), SAT/ACT test prep and test again to maximize the number of schools he could be a candidate and maximize merit scholarship opportunities, work to make spending money and savings, volunteer, continue to develop his baseball skills via individual training, work on speed, strength, and agility, etc.. For game action, in many areas of the country there are fall and winter leagues/programs. Our local college runs a league for high school kids here. In the Spring, there are places to play in a few areas. Adult leagues, college camps, etc. all can provide some game action. My son ultimately played in a SoCal league the Spring of what would've been his PG year after we left IMG.