So the area Chris and I worked on has a seam between the masonite used on the helix and the new OSB, and a couple of tracks will need to run across that seam. While it's a location where people won't lean or put any pressure on it, I wanted to stabilize it a bit. These will be simple splice plates glued on since there isn't clearance for anything else. You can see the mockup of the sidings here while I test whether an Atlas crossing will work in this location. There are a number of commercial options, or I may just handlay it.
Since the OSB is thicker than the masonite, I need to glue a couple of spacers first, and then the splice plates. But the problem is the same - there's no way for me to clamp them that far from the other edge of the OSB.
It's not too big an issue, so I started looking for some scraps of wood to stack underneath them, and then thinking about getting some measurements to cut a few pieces. While thinking about it, I was also thinking about cleaning up the basement again, and looked at the pile of track I'd pulled off the west end.
Aha! Instant "clamps." And it works very well because the rail is flexible so I could cut it a little long and keep some pressure on the spacers while being glued in.
For a neater approach to the same thing (which apparently are spring clamps), check out Joe Smith's use of pieces of masonite for another option.