I once drove 1,800 in one stretch (taking short naps in the car) when I was younger, but I can't do that anymore. The best part about a camper is you can stop and take naps in comfort. I just drove 550 miles a few weeks ago, I stopped every hour or two and took naps that lasted less then one hour to a couple hours. I can't drive long distances anymore without frequent naps because the pain medication makes me drowsy, if I did not have a camper I would have to pay for a full night in a motel even if I only needed a two hour nap. With the camper I can stop for a hour or two then get back in and drive. Pulling a camper requires concentration and it is foolish to drive when you can pull over and take a rest. My max is one to two hours until I get out and walk the dogs and two to four hours before I stop for a rest or nap.
I do not think in terms of miles I think hours behind the wheel