Another option is to use a Reese Sidewinder pin box. It accomplishes the same thing automatically, doesn't take up bed space and is lighter. It also keeps the back of the pin box from potentially hitting the tailgate or sides of the truck bed.
On the other hand, if you are careful, you probably don't need any slider or other solution. Just pay attention when backing up or making turns greater than 90 degrees. Most of today's fivers have front cap designs that accommodate truck-to-fiver angles in excess of 80 degrees.
I have been using short bed trucks for towing since '88. Back then there were no sliding hitches (manual or auto), no Sidewinder and no curved front caps. My turns were limited to just over 60 degrees and I have never had a problem. Just spent a little extra time jockying back and forth, changing the wheel cut, etc. I still use a fixed hitch today, but if I ever felt the need for some help, I'd probably get the Sidewinder.
Larry Day, Texas Baptist Men volunteer
'13 Silverado LT 3500HD D/A CCSB 2wd, custom RKI bed
'11 Crossroads Cruiser 32MK loaded