The NHSA Site indicates there is snowmobile parking at the Weirs:
http://nhsa.com/visit_trailpark.shtml
Claims it is on Lakeview Avenue near the Weirs Boardwalk..
I forgot about the construction...I will just stay away from that area anyway.
Maybe try Prescott Park in Meredith or the dog track on 106 supposedly has snowmobile parking as well....