epoxy that isn't subject to sunlight

As soon as you start using epoxy resins for boat building, it almost  becomes apparent that other situations could use it.  I am building a exterior gate and made a router screw-up--epoxied another piece of wood in to the slot.  This will be outside but cover  completely  by another piece of wood--will the epoxy eventually deteriorate with no exposure to sunlight???

No sunlight = no UV exposure = no deterioration.  Good to go.