I’ve been to a few and it is not uncommon to have an organized swap meet time, or depending on facilities a table or two on the side where people
leave price marked stuff. One guy brought a whole trailer and people would wander by and talk at his site. Be considerate of the campground, non Gmc
campers, etc and I would think you would be fine.
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1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC