One way schools often get around the "undue influence" rule is having the *parents* of current players contact the families of prospective student athletes they want to bring in. The coaching staff didn't do the recruiting, it was just casual conversation among "parents."
Same thing with players - if Bishop Sycamore's star tight end Jimmy Snatches talks to his buddy, who's currently a backup quarterback at Central City High and says "hey, we need a QB next year. Why don't you check us out?," that's not undue influence. But if Bishop Sycamore's *coach* does so, that's a different story.
Getting your coaches embedded with travel programs or "skills academies" seems to be another way of recruiting without actually recruiting.