Well since you are going to be in a truck camper either loop will be fine but you will find a great deal more privacy in the Shady pines loop.
For any others out there I stayed in the Shady Pines loop with my 40 DP and yes the roads are tight, like most state parks, but nothing that cannot be managed and parking was a non-issue. We road through the other loop and decided it had very little privacy and the sites were very sandy and many appeared un-level.
All in all we will go back to St. Joe, beautiful beach and very quite.
