Did you find and implement a combination of solutions, to get your Scamp to fit your 58" rail height?
I've got the same problem. I have a 2005 Dodge Ram 3500 (single) with larger than stock tires, so the top of the rails are at 58". I'm not sure if anyone has ever lifted their Scamp 19 5th wheel, to be high enough to fit that height of rails.
I found a 1988 Scamp 19 Standard in good shape. But not sure if I could put a new axle, additional lift/spacers, 15" rims and who knows what else, to make the Scamp sit high enough to tow.
I also want to replace the gooseneck connector on the scamp, with a king pin.