I went there myself. No offense to your lack of resources, but visit NE, Roxborough, or South Philly if you want to see what lack of resources is. I hear your library is actually opened and staffed. Go find out how many other public schools in the city have theirs open. As for training in the parking lot, I'd talk to Coach because you're a half-mile jog from Fairmount Park. Would you all be better at track if you access, sure, but for Cross, considering size, you guys are pretty darn good.
As for your improbably successful, give me a break. St. Clair did an amazing job of getting kids to come out (it helps you don't have a ton of Fall teams to compete for athletes) and then making them better. Comfort has continued that. If you see what the common denominators of successful programs are, you have them: good coaching, parent/athlete buy-in, high expectations, a culture of high expectations (which, let's be honest, is what JRM is about), and though there are some poor kids at Masterman, the money and influence that exists in that school makes it much more suburban/private than "regular" public in Philadelphia.
Also, the type of school you are lends itself to distance runners. Endurance athletes tend to be smarter/more self-reliant/committed to academic excellence. Take a look at which teams excel GPA-wise across the country both college and high school, XC teams tend to be pretty high up there. It's why the Ivies are typically pretty darn good as a whole when it comes to distance running.
Look, I gave you guys props, there's a real nice program down there at 17th & Spring Garden, and though you have some of the problems that the rest of the Public League does, you don't have a clue just how good you have it. Btw, nice racing to beat E&S and Central back at Leagues.