My OTTB viewed trails as the World’s Longest Post Parade when I first got him.
What helped me was:
1 - When he (inevitably) started to jig, we went right back to the arena - outdoor if possible, to work.
Of course, if you don’t have a large outdoor to work in that won’t help you so…
2- Go out with an unflappable horse/rider combo.
My SteadyEddie pals just went right along quietly while TB went “What’s that?!?!” :eek:
Wash, rinse, repeat until TB figured out trails were not full of monsters or Start gates.
After several years I could ride him out, alone, on the buckle.
Although he needed a refresher course each Spring - those 1st rides of the season could get a little wild.
From your description it sounds like your horse was doing what he’d been taught to do on trails when you first had him.
After so many years doing dressage, he s/b more relaxed and tuned-in to you and may very well be glad to walk out on trail.
The new barn also sounds like it may provide some riding buddies to help with the transition.
Hope it works out & you get in some nice rides!