How many of the boys you work with are going to be around or be willing to do extra work when not playing?
This has always been an issue, at least where I am.
I started an offseason program once several years back. Bands, Jobes, plyocare work, weights, sprints/conditioning, med ball work, long toss, flat grounds ect. Free of charge. Three nights a week. Had access to the local high school field. Started with 6 guys or so…by he time week 4 came down to 1. Most kids are not very dedicated.