I'm a regular at NHMS for the July race. You can enter the speedway property a week in advance. The Sunday before the race the track opens. The choice you have in parking is limited to the Lot only and not a particular spot. Some lots are more level than others. STRONGLY recommend bringing many leveling blocks to ensure getting level. Be prepared to be packed in like a sardine, for noisy generators and a good time (that is, if you're a race fan).
Any other questions? Fire away.
1997 F53 Adventurer 37rw
IAFF L-792 (Retired)