As part of my self assigned pre-build TD research, I have been going through many older threads in both the chassis and construction forums.
I found an older thread about Redtrailers in general with a small bit of discussion on lengthening the side rails.
http://tnttt.com/viewto ... c&start=75
Mike's generic Benroy plans actually lit this idea. He shows using one of the crossmembers used to make the trailer non-folding. I got to thinking, why not use two of them to add the 19" I need to get the 115" length used by the 10ft Comet. After all, as stated in several places, the TD body torsion box has much of the strength. The frame is a convenient attachment point for all the bits.
No, I don't expect the side rails to be able to carry the full rated load, if used as a utility trailer, when it's extended as proposed. I do plan to do a 2x2 wood frame and 1/2" plywood deck floor and go vertical from there.