Leave it to Jack to provide a different point of view.
We were staring at the progress last weekend while having a drink, and suddenly he says "you should just make it a lift bridge that gets pulled up by cables and stored against the ceiling."
Jack also made the point that by having a vertical lift, we could much more easily open and close during a session, so perhaps we could use one of the tracks in the new yard to the left to store Amtrak or a short regular freight train as needed, freeing up an Island track for more consists. The bridge itself will not have trains on it for storage.
And after a night spent painting the sides to match the fascia and the underside to match the ceiling, I had to concede this was a better plan. More work now, but less chance of damage later. Thankfully, the side girders are sturdy and plumb, which will allow vertical cable attachment without an issue. And the apparatus should fit above the drop-in ceiling, with simple holes cut to allow the cables to extend below and be affixed to the bridge.
I checked online for lift systems and found a good one normally used in garages. I think this one is going to work out.