Nice! Looking forward to seeing how this turns out!
Tempcoat is another insulation product you might want to take a look at. I haven't played with it yet, but one of their distributors is in the next building from my office. From what he's told me its a silica based product added to paint. Used on the interior of a home it looks just like house paint and can be painted over if you want but adds another 5% or so of insulation. A bit more insulation for virtually no weight addition seems like a good idea. Not very expensive either... $60 for 5 gallons, IIRC... I've been toying with the idea of doing the underside of my roof in the attic (after I replace the roof in the next year or two).