Agree with Vulcaneer. Everyone may have clearance when the truck and trailer are level. That 3" clearance between the front of the trailer and back window will soon disappear if you are backing into a site that is slightly up hill. If those trailer tires are 3" above the truck tires then the 3" clearance is gone.
For the little extra money for a manual slider, it's good insurance.
Definitely true.....except for the manual slider. The slider would not be used in this case which is why I went with the 5th Airborne Sidewinder.