Not sure how all the manufacturers handled this, but Classic Roadsters Duchess provided a backing plate that hangs between the inner bends of the front bumper spring mounts.
It’s basically a steel tube with a piece of flat steel (about 2 inches by 8 inches welded to it. A threaded rod passes through the tube and through holes in each bumper mount and is secured with acorn nuts on the inside of the bumper mount.
Should be pretty easy to fabricate.
I see some TDs with the front plate attached through the chrome bumper face. I think it looks better handing below the bumper. You can’t see the bracket, but you can see where the plate is mounted on my Duchess in the pmossberg folder.
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica Roadster
If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)