I am remodeling a bathroom and am going to add a light in the shower. I will use a wet location recessed light. Current code requires this be on a GFCI breaker. However, the breaker serving this circuit is a half size GE. I haven't seen a half size GFCI breaker at the box stores. That certainly doesn't mean one isn't available but I haven't looked further yet. I can replace a receptacle currently in the circuit with a GFCI receptacle and protect all of the lights/heater in bathroom including the shower light in that way. Would this be an acceptable method? I feel like it would protect me but is it in the spirit of the code.

My other options would be to 1) find a similiar load on one of the full size breakers and swap this circuit to a full size breaker and then replace that with a GFCI breaker. I do have a few full size breakers. There are no empty spaces in the panel.

This is in a 100 GE amp panel with 20amp breakers, about a 1983 model.

Thanks

Gary