[ERASER5]

First guess is April Fools, but...

Considering that the short bed is rarer and more sought after, selling/trading it for a long bed would be far faster and cheaper.

But if you must, long bedsides are available as well as long bed floors. Adding to the frame will require 2 welds on each side right where the load strees is, as well as 2 welds behind the axel. A long frame swap would be better in my opinion.