[mark poulson]

Twenty baits! Man, you are ambitious!
I only mix up enough to do four or five jointed lures at a time.
Here's something I thought of when BobP mentioned that heat sets off epoxy.
I know from personal experience that the epoxy cures more slowly in colder weather. In the winter, I use a hair dryer to make my Etex flow more easily.
You might try putting ice cubes and a little water in a larger dish, and setting the epoxy mixing cup into the ice water, to slow down the rate at which it goes off, while you're coating that many lures, to give you more working time.
If it's too stiff, you can hit it with a hair dryer once it's on the lure, to soften it up and make it more spreadable. The ice bath should keep the mixing cup stuff from going off while you're using the HD and brushing out the lures.
Try it once with a small batch to see if it works first. I've never done it myself.