Do whatever you can to get one of the football coaches on your staff. Doesn't matter whether he knows anything about the sport; you'll train him, and you won't put him in situations where he'd be embarrassed, right? (Actually, in my experience football coaches often bring a lot to the table in terms of organizational/motivational expertise and can make a real contribution.)
Y'know what, let's cut to the chase:
Sit down with the head football coach. Let him know that some of his guys "are considering" coming out for track, and ask him (get HIS input on) what kind of conditioning he'd like to see his guys get. Try to make it a partnership.
In other words, spend your time/energy "recruiting" the coach, before you try to recruit his kids. If the coach is really a problem, even when you're trying to be cooperative, then you may have to "recruit" your AD--assuming s/he isn't also on the football staff...
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Easy advice to give, but I know it's not always easy to follow. The early-specialization crap--junior high kids on traveling teams in basketball and soccer, for example--is actually killing kids' long-term development. (By "long-term" I'm only referring to their HS years, not what they'll do in college and beyond--only a tiny fraction do college sports anyway.)
The Soviets, BITD, did some great studies showing that adolescents, esp. the younger ones, benefit more (in their specialty events!) from many-sided development than from early specialization; and the advantage shows up as early as their second year in The Sport.