I used your method, modified a little to put these gold colored tissue (not foil or plastic) letters on my Brown B-2 racer.
The main difference was that large letters really want to tear and fold in on themselves when wet or glue-sticked (verb?) and are very difficult to re-position. I finally had to dispense with the glue stick and white glue, and float them on generous amount of Polycrylic applied to the wing. I could then reposition slightly.
I also used the paper pattern sheet cutout as a positioning stencil to place the letters.
The photo shows them as first applied -- the slight wrinkling disappears after overnight drying.