I doubt they've opened their gate, I'd expect any new development to be along the utility corridor sort of continuing the trolley trail. Even if that's allowed it's rugged and probably overgrown this time of year.
Costs you little to go look. If it's closed just go back over the covered bridge and enter public Haley Farm at the green vehicle gate, down hill on reasonable gravel. Probably find a huge mud puddle where it levels out right now, but people walk around it on fallen branches in the woods. As you probably know that then lets you ride up through more normal subdivisions and take 215 scenically along the coast to Mystic - all you really miss is GLP itself, which can be reached if you really want to circle it from 215.
I suspect but don't yet know for absolutely certain the the parking lots of regional Grasso Tech before Fort Hill somehow connect to the new town school on top of it. Last time I detoured up there after failing on the hill they were doing construction on what looked like a drive but was fenced. Came back out and made it up the hill on route 1 after all.
If you have time another nice detour there is to take (paved) Gravel Drive a block before the Mystic drawbridge, go up around the Mystic River estuary to old Mystic then come down the far side past the seaport. It does bypass the village but you can duck in before or after. Or if you find the bridge up.
I'd also go through Avery point to bypass most of Groton city, but have probably said that in previous threads. There are decent inland routes too, like Tollhouse to 184 to Old Mystic or even further north towards Foxwoods.
