First appointment of the day cancelled... so...
For all the contact info for the seashore....
email direct from this website:
http://www.nps.gov/caco/pphtml/contact.html
snail mail:
CCNS ORV Management Plan
99 Marconi Station Site Road
Wellfleet, MA 02667
Your letter will go to the acting head ranger, and he will get it to the committee that is charged with coming up with recommendations for change. I know a couple of the people on the committee, and they will consider all you send.