You could likely use any low viscosity epoxy. None of the "finish" epoxy are going to be 100% solids, so you end up paying for solvents which are relatively inexpensive and you still have to thin them down further. Look for an 100% solids epoxy with a CPS of 400 or less. Some of the epoxy's made for vacuum infusion are very low viscosity. If you plan on spraying your finish, you will have to get it down to below 100 CPS, or about 17-20 seconds thru a #4 Ford cup. Smooth-ON makes an epoxy thinner thats not a solvent.
You could use it to reduce the initial viscosity, which would reduce the solvent load. If you want UV resistance you will need to add something to absorb it. Contrary to various claims, their is no magic UV blocker. Its always something like pigment or fumed silica that absorbs or reflects, only to some extent, the UV rays