outdoor GFCI tripping at the breaker box and not the receptacle?
GFCI receptacles and standard circuit breakers perform different functions.

A GFCI receptacle measures current going out and current coming back and if there is more than 5ma current difference between the two it trips. This is to prevent electrocution of people not overloads or short circuits.

Standard circuit breakers have two methods of tripping and are designed to trip on an overload, high current ground fault, or short circuit. The overload can be just slightly higher than it's rating. The ground fault or short circuit can be hundreds of amps in a residential panel.

So, if you are tripping the circuit breaker it is possible you are just overloading the circuit. In this case a GFCI receptacle will not trip.

Good luck!