Hi Rick,

Brilliant idea!
Another option (to avoid having to rely on either the existing plastic post or catches at all) would be to fabricate two supplementary U-shaped metal brackets together with a new U-shaped metal wire post (similar to your existing design).

One new supplementary bracket would be installed under each existing catch using the existing mounting screws (one under the trailer body catch and one under the door catch). Each supplementary bracket would mimic the shape of the trailer body bracket i.e. be U-shaped with two ears sticking out slightly beyond the existing catches at a right angle to the base. A hole in each ear would allow each U-end of the new metal wire post to be inserted into the two mating supplementary bracket ears at each end - and be held in place by a tight sliding friction fit.

Gary (kngtek)
Calgary, AB Canada