I don't feel like I've improved upon the mod enough to publish my own version (yet?), but I have uploaded it unlisted in order to demonstrate how you might make this mod more resilient. I will post a link to it below. Feel free to delete that post (or this whole thread) once you're satisfied.

As a brief overview of the difference between our versions: it's really only the railing_rep_side* meshes that need to be edited to achieve this bridge style. Otherwise, some small config tweaks bring about the rest of the effect. Shipping only the *.mdl files necessary to support the edited meshes reduces the number of contact points between a piece of the mod and a piece of the vanilla game, which should cause it to be more resilient to future game changes.