I don't know about the others but we have done both, paid on a day to day basis(we rarely camp in one spot more than 2-3 days) or paid in advance and simply not worried about losing a days fee, especially if we are far enough away that the cost to drive back is a wash or there was a reason to return home earlier than anticipated. Either way it's never been a problem.
When we leave camp for a day of fishing etc., we make sure to not leave anything of value behind. Though we have a 5er, I might leave a radio on and check to make sure my camp reserved envelope is still in place..
When we are in a privae cg, like a KOA , for example, we will often leave two chairs at the site, and a ground mat. Sometimes, we will also leave our (securely locked) bikes.
When in a public camping area (National Park, eg) we will usually leave a really small cheap tent set up (even though we never use a tent) We tried the "campsite Occupied" signs, but they did not always work. The tent always has (so far)
Alaska is next! Still trying to fit the pontoons to the RV so We can get to Hawaii!
We have had relatively poor luck with our campsites when we have left them, compared to most here. In 3 years if sporadic camping (total of maybe 50 nights) we have had two incidents of our stuff being molested. The first time was in Custer State Park in South Dakota while we were out siteseeing. The camp hosts caught a group throwing our leveling blocks and entry mat into the woods with intent of taking the site, and probably the stuff when they left. The second time was at a Provincial park in Canada. Same thing, out siteseeing, came back after only two hours and our expensive, folding, entry mat was gone. This was with campers within 50 feet on each side and in the middle of the day, Luckily, they didn't see the power cord.
We now pack up anything of value when we leave, mark the site with a cone and a cheap mat marked with our name and "site occupied". Hopefully, our luck will improve!
We have a class B and leave our cheapie folding chairs.
Not my cute little lightweight aluminum folding table, ideal size for our van, though as I think it would be harder to replace. I'm quite attached to it.
We do carry an orange cone marked occupied and use it for very popular campgrounds where rangers tell arriving campers to look around and pick an open spot, then come back and pay. Helps other campers quickly see that it isn't open, too, easier than looking for those little papers clipped to posts.
We use a small "OCCUPIED" pylon bought from Northern Tool. On the opposite side to discourage theft we have our last name. We use it when finding a site in a large campground where you have to go back and register. So far it has worked during busy times.
We left out a mat to mark our site in a private campground and it was stolen. I'm beginning to think a cheap, small tent might be the way to go. That is usually the only recourse for tent campers and they seem to be more respected than trying to leave out things that can be stolen or to be assumed a left behind item like blocks and mats. I'm reluctant to leave our $50 camp chairs out.
2011 Great West Van Legend Sprinter B Camper Van
Visited states in an RV
You can purchase plain barricade tape, or caution tape, and string it across the campsite. I'm not sure how long it'll stay up in State or NP parks. The park rangers may not approve, but worth the try. I would think the "caution" tape would deter anyone from entering the site. If you decided not to return, it wouldn't be a big deal. Except to the park rangers, who will be confused for several days wondering why there is "caution tape" strung across a campsite.
Jim & Darlene
Pickles our Teddy Bear
2013 Roadtrek RS Adventurous (aka..Roada)
Wisconsin Dells...Water park capital of the world