Dumb question for Brian - do you have to roller on epoxy or can it be sprayed on?
I use epoxy for some other things I do, and I've always wanted to spray it in some circumstances--it has never worked out.
1) It is viscous, so to get a consistent and thin layer, you have to compromise the overall integrity of the epoxy, or you have to get it hot. And if you get it hot in the spray gun pot/can, it will cure really fast, and then you risk thermal runaway. There are special spray guns that heat the epoxy just before it hits the spray gun air cap, so that is a special, but possible option. I've ruined a spray gun because I did not get the epoxy out of it fast enough, and I locked up the gun, and created some thermal damage.
2) It is messy and gets everywhere, and if you don't 100% clean things right away, they can be ruined. Epoxy is very tough, it sticks really well to most things, and it gets everywhere.
3) The overspray is now going to be another challenge. If the wind or a missing mask allows the epoxy to get places you don't want it, it is probably going to be there for a long time since epoxy is very good at sticking to things.
4) As Brian says, rolling is pretty darn effective, gives you a fairly consistent mil thickness, is fast, wastes very little epoxy, and clean up is basically throwing out the brushes/rollers.