geysergazer posted:I'd think about screws from the back side through the plywood and into the screw holes in the Fastrack pieces. Viewing a Fastrack piece from the backside this is what you see:
The screwdriver tip points to the mounting hole.
I would first attach the track to the plywood in the conventional manner, driving screws through the Fastrack mounting holes and through the ¼" plywood. I would then stand the whole thing vertically to provide access to both sides. Next I would remove one screw at a time from the track side and drive a slightly larger screw through the hole on the back side of the plywood and into the Fastrack mounting hole.
Oh, and I find ¼" plywood to be just fine for decking. In my case I simply drive screws through the plywood because the underside is open, unlike your situation wherein the floor will be immediately adjacent, thus the need for no protruding screws.
I was thinking of this same solution - the screws from the top are a #4 -3/4" flathead Philips sheet metal screw - you will have to test a screw from the bottom possibly a #6 of the same type and determine if it splits the plastic screw bung.
Screwing from the bottom will be secure. 8 pieces of O36-45° will make the circle with 2 screws in each piece.
Another though is to router or chisel a channel on the bottom for the power feed.
Rounding off the sharp corners may also be a good idea.
