In years past I have always been able to leave as is until I return home, so I don’t have any tricks for that.
As far as prevention, I’ve found that a cheap nylon cutting board cut down and attached between the camper and wheel wells makes sliding the camper in a lot easier and helps keep it centered. The real solution though is to install a horse stall mat between the camper and truck bed floor. Those things hold the camper in place like glue!
On my first trip after installing the mat, I had a turnbuckle come completely loose somewhere between Saline Valley Springs and the top of the hill at the Bristle Cone Pines via North Pass and the back way from Laws to the Pines. A fairly steep bumpy route, and though I don’t know exactly where it came loose, that camper didn’t move at all. In the years since I’ve had no problems with movement, so I’m sold!
Hope this helps,
Tom