Trotter scalping

Does anyone have ideas how to stop trotter from scalping off side rear .
Tried bar shoes on rear.
Now have trailers on behind medium middle rounds on front.
Still hitting .
Any ideas would be greatly appreciated.
Cheers
Mal

what sort of trailers behind , im not a fan of double trailers cause more issues than they help ,if they can handle it go lighter in front, or try square the toe in front to break them over quicker ,, what sort of crupper are they wearing ?thicker crupper to get them wider ,lower them on the inside behind as well ,
there are lots of things you can try ,hard to diagnose without seeing or driving the horse exactly what would work

Only single trailers in behind.
Got thick crupper on him.
Thinking to try the rear spreader . Heard different reviews on rear spreader.
Got medium half rounds on the front.
Problem is the off side front paddles out and the off side rear sometimes come inside or hits the front as it comes down .
He dog trots or short strides in behind sometimes and other times the offside rear will bang the off side front.