The below picture shows my plan for holding the rails in place while I'm gluing them down (the 2"x4" wood will be covered in masking tape, just in case). I am going to glue the rails on in two phases: the rail-to-deck flat joins first, followed by the under-rail-to-float-edge. That way I can control the rail positioning exactly during each phase.
A view from the long end (the rear of the rail is not clamped down so it torqued out of position a bit, which is why it doesn't look parallel to the float centerline):
I need to trim off the excess on the bottom of the under-rail supports, and you can see the line I drew on the rear-most support in the above picture. Anyway, hopefully I'll get the rails all glued and taped on this week, and be fairing by Friday.
One other thing I forgot to mention last night. My HVLP spray gun came with a 1.1mm nozzle\needle combination. The literature for Alexseal's high-build primer says you should use a 2.2mm set -- wow. I couldn't even find an Accuspray "Prokit" in that size, so I settled for a 1.5mm set. Long story short, when I tried to spray with the 1.5mm nozzle, it felt like I was guiding a fire-hose (and this is what contributed to most of the overspray, I think). After my first coat of high-build I switched back to the 1.1mm nozzle (guidelines be darned) and it was much better. When I bought the HVLP kit, the technical guy at AxisPro told me that the default nozzle was "good enough" for most applications and based on this experience I guess he was right.
One more comment: Saturday's high-build spraying was my first opportunity to use Alexseal's "primer accelerator", and I was curious to see how much of a difference it would make. Well, when I sanded down the high-build on Sunday, the primer was nice and hard, and I had much less clogging of the paper to deal with. Two thumbs up! :-)