Called Gasquet Ranger District Smith National Recreation Area 6-17-19 and was told showers are for everyone, not just campers.
The showers are quarter operated and it's not posted for campers only that I remember.
I don't see why you wouldn't be able to. There is overflow/guest parking. I don't recall seeing any signs saying the showers are for campers only. But to be honest, I don't know for 100% that it is OK. If you go and try to shower, please let the rest of us know if it's OK for sure or not.
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