Even the best epoxy primers do not have the UV stabilizers in them for even short term use.
Not entirely true.
SPI's Black epoxy primer does have UV protection in it and will last for several years with no issues.
I recommend applying 3 coats when you get the piece ready, then you can lightly hit it with 400g prior to painting, then your ready to go with a sealer (The same SPI epoxy reduced) and your final paint.
SPI makes a Flat paint as well.
