Homebrew PCBs

With all this talk of "proper" solder masks, I thought I'd ask about  
some more rough-and-ready options.

I've just successfully replaced the guts of my bike's tail light (with  
a PIC 12F6x and a lot of 0603 LEDs). Although it's sealed into a  
watertight box, I'm going to need to seal the copper against long term  
corrosion. It's a nice small board so I'm thinking of either painting  
it with urethane (e.g. varnish) or I thought it might be more durable  
but viable (given the smallness) to just paint it w/- araldite - a  
crude but effective "2-pack epoxy". That would write off a paintbrush,  
but be pretty tough.

The reason for painting is to avoid the LEDs, or I'd just dip it.

Anyone tried it? Am I crazy? etc?

PG