being as you have NOT said where you are at......this place may be way on the other side of NA from you. But there is a place in Bellingham Wa that makes reasonably priced custom trailers. My step dad bought one last summer for his boat. Mid 3000 range IIRC for a 6500 lb 26' on deck rig.
They use old MH axels, all electric brakes etc. On ST's, they put the axels a bit too far forward, and we will adjust the back about 2' to get the proper hitch wt for towing longer distances.
She drives me boat,
I drives me dinghy!