I positioned the U brace for the springs 19 1/2 inch from the end of the trailer frame. That gives about and inch clearance for the door from the fender front edge. With the tongue box and small vestibule I added, this put the tongue weight at around 60 pounds with the TD unloaded, which is in the 10 to 15% to the overall weight that is generally recommended.
An added note the stock fenders would rub and rattle against the TD sides. I put a strip of foam weather stripping between them and solved the problem.
Hope this helps.