If you don't need hookups, I would stay at the track. There should be quite a few staying there. For anyone coming in Friday Night, the track wants all RV'ers in by 8pm Friday night as not to interfere with a convoy of rigs that will be showing up then. Otherwise, you can show anytime after 7AM Sat. morning and camp Sat. night. Camping should only be $10 per RV, and its $15 per person for a weekend pass - pretty reasonable if you ask me.
If you need hookups, try checking in Acton, there is a Thousand Trails and some others, those are about 10-15 minutes from the track. For those entering the show and shine, that is on Sunday morning, so be there early so you don't miss it.
Craig