I was stationed north of Baxter State Park in Maine from 1959 thru 1962 at Loring AFB.
We visited several times with our gear in a station wagon... I was with Ernie Fauson and his family. It was primitive.
Janet and I went thru the park in 1965...
It never occured to me at that time that I'd ever be there with anything too big to get in...
Janet and I were there in 2010... we didn't even try to take our TC in... we are 27.5' long, about 8' wide and almost 11' tall.
I could have unloaded the TC, bent the rules and toured in the truck... but I feel like they have the rules for a reason...
While you are up that way... have a look at the Allagash.