Tough situation, but I think it's fixable.
Did you use Future to prep the canopy before you masked and painted? It makes situations like this a little easier, because there's one last protective layer to protect the plastic.
I've heard some people mention a product called "Goo Gone" to remove masking tape residue. It's an office supply type of product. I've never used it, but I've been told that it's strong enough to remove the residue. However, it's delicate enough not to damage plastic or Future'd over clear plastic.
The thick paint that's hanging over is a little tougher. I guess you could use a Hobby Knife, but you'd need the knife control of a surgeon. I have a 3 grit sanding stick (OK, It's a fingernail polisher) from "Sally's Beauty Supply." Its smoothest part is a fingernail buffer that is will buff away problems with clear plastic, but it takes some elbow grease. Whatever you do to correct the paint overhang, BE CAREFUL. If you do mess something up, make it as smooth as possible with a fingernail buffer and then apply a little future with a Q-Tip. The Q-tip should be just barely wet with the Future.
I recommend clear Frisket Film for remasking. It's clear so you can see where to cut and it masks well. However, it doesn't get around sharp bends very well, and it doesn't adhear well when set to mask areas with very small surface areas that bend. However, it'll most likely work well for your HH-3. I love the suff. I buy it Michael's art supply.
However you fix it, Good Luck. We've all been there.
Semper Fi,
Chris