Help - Pathing for a custom bridge

[Nightmare_Mode]

Hello

So I'd like to make a custom bridge that's much longer than the stock ones available.

Creating the object itself and applying a model is no issue. I know how to do all that.

The pathing is the part I can't figure out after searching the forums.

I can make it LOOK like there's a long bridge but of course I need the units to actually walk all the way across it. I don't know how to do that. Any suggestions would be highly appreciated. Thanks.