Updated 6/11/2016:
There were a number of things (activities, decisions) that I forgot to mention last night.
First, earlier in the week I did some test-fitting of Backdrop #4. I removed a part of a support for a track in the hopes that the stand-in for the backdrop would fit into the available height between the support and the ceiling. As you can see in the photo, it does not. It will need to be trimmed. I will re-install the support and then measure and cut the backdrop at the bottom.

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Second, because of fit and placement issues with Backdrop #3, I've decided to modify the Hidden Passing Siding, closing off the eastern entrance, and transforming it into a trailing point spur behind the backdrop. This was done because it would have been difficult to provide enough clearance for locomotives entering the siding. It is also the expedient thing to do; in a year, retirement is going to change everything. The larger goal is to get the backdrops installed, the bridge placed, and run some trains.

- W_Rebuild_90_.JPG (34.04 KiB) Viewed 3129 times
Clearance behind Backdrop #3 was checked for both the lead to the Hidden Staging Yard and Hidden Passing Siding (which was identified above as a problem). This photo shows the mounting cleat (just to the right of the backdrop where the ground meets the sky) installed last night. This cleat, along with another piece in front of it, will form an anchor point for the rightmost lower corner of the backdrop.
I also picked up some more Velcro today.
George