Well, I finally got a couple evenings, uninterrupted. Strongback done, stem ends done, stations clamped in place. Just lining up the centerline of the station molds, with the centerline of the strongback, and running a temporary string across the tops, all stations are in line within 1/16". Stems are square and plumb back to station 6 within 1/32". I was going to take everything off to use the strongback for ripping strips, but I'm still up in the air on table saw. If I use skilsaw method, I'll lay a 20' ladder on a couple saw horses, and clamp my sacrificial 2*4's to that to rip on.
Here's a question. Everyone talks about leveling the strongback. I started doing this, and it is very close. But for alignment, I'm using squares, string lines, and measuring tools, not too much level. I feel it is much more accurate. Even a 6' level, and a keen eye are only going to get you within 1/16" per 6 feet.
As you can see, my alloted build space is rather tight. I'm thinking of moving it all to the second floor of my garage. Much bigger, but then all the stairs, back and forth to all of the power tools.

