If you're not going to use the WBPU method, then go over to airfieldmodels.com and look at Paul's method for glassing.
I use the EZ Lam two part resin from acp-composites.com in Livermore, CA. You can use either .5oz or .75oz fiberglass cloth (available from ACP or find it on Ebay). The resin is mixed two parts "A" to one part "B". The big decision then is do you dilute it with some acetone, or just put it on full strength? I usually put in little acetone (~10%), some folks dilute it more, and some put the resin on full strength.
I don't treat the sanded balsa with anything, nor do I use hairspray to hold the cloth down. I cut a piece of cloth to fit the surface, smooth it out by hand, then brush on the epoxy, working from a strip down the center outwards to the edge. Once the cloth is covered, use a plastic credit card to squeeze excess resin out of the cloth (I go over the cloth from center to edge, then lengthwise, then diagonally... the more you get out, the less weight you add). Then use a roll of toilet paper to soak up any extra.
Once this has dried, you can lightly sand the edges of the glass (220 grit) to feather the edges, then flip the part over (a wing or stabilzer) and lay down the next stip of glass. Once you have the entire project covered and it's dry, put another layer of resin down, again squeezing off as much as possible. Once the second coat of resin is dry, lightly sand the whole surface with 220 grit abrasive paper and use primer to fill the weave of the cloth.
Using the resin method takes more time than WBPU. It's not any more difficult, but takes longer to dry. Either way, you then get to do the "put on primer and sand it off" routine so many times you'll look at a roll of Ultracote and question your sanity for even thinking about paint
As for the masking problem, one thing to try is to mask off the surface, then spray a layer of clear coat or the underlying paint color over the edges of the masking tape. That seals the paint line, so your top color shouldn't bleed through.