Point of Interest(POI) GPS

I'm going to use my popup pickup camper to take a road trip. I'll start in Denver Colorado, go south through Texaes , then east along the gulf down to Key West. On the return I'll be going the northern route Tenn, Mo, Ne. Love to camp in the state or federal lands. I have a number of hand held gps's that I use for hikeing and a Garmin automobile unit. My question is; is there a point of interest memchip or some other way to load my gps with state park and federal land camp grounds? The car gps is a Nuvi 360. But I'd like to get a newer model.