Another suggestion:
You could use a Lionel girder bridge ... MTH and Marx made these as well. I don't have a photo of one but this bridge is basically a flat surface with a girder on each side. Depending how wide a space you want to bridge these bridges ( as all bridges ) can be used in multiples. Many were/are made since the PW era. You could paint over any printing on the side of the girders. I see these kinds of bridges being sold new and used at train shows. I believe the girder bridge are/were also manufactured for double track?