I would need to measure it when I get home, but the depth is probably about an inch or so.
The existing outdoor outlets on the circuit are not GFCI, but the chain includes a basement bathroom outlet, which is GFCI. I found this out one time when the balcony (or perhaps more accurately a covered wrap-around porch) outlets were not working and the breaker was fine, eventually found the GFCI in the bathroom had tripped.
The existing AC duplex is not WR, but the enclosure/box/cover is.