What about any other gear that you carry to your stand with you? Fanny pack? Backpack? Etc. From the sound of your scent-control routine you're pretty much in line with what I do, and have had success with, so I would imagine that you've thought of this already. But just in case, it cant' hurt to ask.

I spray my pack down before every hunt, and keep an HS Earth Scent wafer clipped on my pack for some extra cover scent as well. I also store it in a plastic rubbermaid container when not in use. I know it's not scent-proof, but it's better than leaving it lay around in your truck, garage, or house.

As you pointed out, the boots could be a pretty good contributor to your problem as well. It doesn't take much of a hole for a fair amount of scent to squeeze out as your' walking. Especially as your feet begin to perspire. I would definitely replace the boots if they have holes in them. It certainly cannot hurt.

The last piece of puzzle I didn't see mentioned - a facemask and some Gum-O-Flage. Scent-Lok hats are great, but if you don't have something covering the rest of your face, and especially your mouth/nose you might as well not have anything on at all.

That's all the insight I have for now. I don't think you'll EVER totally eliminate your scent and since these deer aren't freaking out and running to the next county I think you're on the right track to being effective. I would try my suggestions and see what happens. If you've got the same results, it could just be that you're hunting some nervous, pressured deer. In that case, any amount of human scent is going to put them on alert.