E.H.
Hi D.-
Try sites in Dillon, the next town over. Here's a link to camping in Dillon:
http://www.wildernet.com/pages/rectype.cfm?areaname=Summi...
Some of these campgrounds accept reservations. You may be able to call and find out how far they are from Frisco.
Have you been to Summit County before? If I'm telling you what you already know, I'm sorry, but camping in that area may involve some cold nights, even in summer, so be forewarned.
Good luck!
E. H.