So what your saying is "Craft (Item) and have (Item) be interactable? In this case a bridge, that they could walk on. Hmm. I believe some Modders cracked that a while ago (A15-17) but I am not sure of specific mods. A good one to look at is @Spiro 's Door Mod
He has your basic idea Down, craft a door, have said door interact, it might not be a bridge, like you are asking, but the general Idea is there.
My best guess would to frankenstein (Snip and Copy) the code to the bridge you are asking for, and see if it works. I have tried this before. They would just walk over it if they could, but designated as a specific interactable is beyond me. Sorry if I couldn’t help you.