It sounds like it should be a good fit from the dimensions. I ran my deck stringers to the beam ahead of the foot rest like you did because I was worried about having room for my feet, but as it ends up it's more comfortable to paddle with my toes pretty pointed, and it's nice to be able to put my toes on top of the beam for "leverage" (but really just to help keep me locked in even more) when I'm rolling. I guess the bottom line is that I didn't really need to run it up there, but it was my first, and definitely not last, boat, so there are a LOT of things I'd do differently. You'll be able to tell when you saran wrap it if your feet will fit the way you want or not and if you need to adjust the masik height, but I didn't figure out my foot issue until I'd paddled it for a while with the final skin on.

As for coatings- I did a ton of research into coatings and fabrics, and I think that there are two guidelines you should follow when you pick, no matter what your other criteria. First- will the coating stick to the fabric, and second- will the fabric stretch more than the coating.

Not all varnishes or paints will stick to polyester or nylon, and if the coating doesn't stick, it will eventually delaminate. If the skin is more flexible than the coating, the coating will relieve the stress by cracking. In either case, you can switch skin materials to a different fabric/coating combination that will work well together, or you can just enjoy it as long as it works for you and then reskin it when it fails. Reskinning gives you a chance to make sure your frame's still o.k. or to make changes, so it's not a completely heinous thing.

In general- canvas is the least stretchy and pretty much anything will stick to it, polyester is moderately stretchy, but many products intended for use on wood won't stick to it, and nylon is very stretchy, and again not all products will stick to it or be as flexible. Depending on the specific fabric you're using, nylon stretches up to 300%, which is why it's so good at puncture resistance. The trouble with using Zar on nylon is that Zar is designed to work on wood, and the maximum possible seasonal movement in a piece of red oak is 2.5%.

The only common coatings that are a match for nylon's stretch on paper are Corey's goop and Coelan Marine Coating. Coelan was actually designed for use on flexible fabrics, and flexes 300%. It's one-part and goes on like any paint. I've only done test samples, but I'll use it on my next SOF. I've used Corey's goop, and it's tough. It's tricky to put on so that it looks good, especially for a first timer, but it will still be tough even if it's ugly (like mine). Just a word of advice on the Corey goop- I am very fussy. The people I know who used goop on their boat and had it turn out great the first time were not too fussy. Extrapolate what you will, but the boats look about the same from 5' away. I don't know what the specifics are on its flex, but it's pretty good, and is intended to be used as a SOF coating.

But- don't take my word for it. Call up the manufacturers of the coatings and ask them. Things are changing all of the time and they'll know best what their stuff can and cannot do.

m

(BTW- I've only used Zar and Minwax Helmsman on wood, and only once each, but I liked the Helmsman better.)