I followed the Kuffel Creek plans when I made the frame. Overall, the plans are good, with two exceptions.

First, the tongue or draw-bar is made from 1½" x 3"
channel which is then laterally stiffened with 1"x1"
square tube. The tongue is 13 feet long, and runs the
full length of the trailer. I think that the designer
intends this channel as a pathway for conduit which
carries wiring to the rear of the trailer. Having built
 this trailer, I now think I would prefer to use 2"x3"x¼"
rectangular tube. I would use just a 5 foot length and
 have it extend only as far back as the second frame
cross-member, two feet from the front of the trailer. I would have it oriented so the 3 inch dimension is vertical. I would
still use the 1"x1" tubing to stiffen the tongue laterally.
The rectangular tube would end just at the front of the
trapdoor framing.
My wiring runs through the body of the trailer, so no pathway for conduit is needed.
Second, the plans have a framed area between the second
 and third cross-members for an optional "basement"
which, when the trapdoor is open, gives an additional 4"
ceiling height — so that you could use a portable toilet
inside the trailer without bonking your head while in
thoughtful perch thereon.
  However, after a season of using the trailer and the portable
toilet, we used a different system altogether.  We set up a
tent alongside the trailer, as another room. The toilet is in
the tent, and is then available night or day. On the other
hand, an underfloor storage space might be kind of nice.
It would be possible to make an underfloor space about
8 inches deep in this area if the trailer tongue were not in
the way.		 The axle tube determines what the ground clearance
of this trailer will be. Any space between the axle tube
and the underside of the trailer floor could then be used
for storage. With the axle arrangement in these plans, I
have about eight inches of space. As time permits, I will
modify the trailer tongue to give me this space.
As a track welder for a local railroad, part of my work was
some heavy-duty oxyacetylene welding on both mild and
medium carbon steels. I had a gas welding rig at home, and
so I chose to gas weld my frame. I did not relish the thought of
lying on my back to weld the undersides of the joints, so I
would turn the frame over, instead. As the frame got too
awkward to turn over, I rigged a block and tackle to hold one
end at the trailer centerline, while I held the other and rotated
the frame.
As careful as I tried to be, I still managed to warp the frame in
a couple of places, due to the effects of heat. I had access to a
small section of deserted railroad track. I parked the trailer frame
over the rail, chained it down in the appropriate places, put
some stout jacks under other places, and straightened the frame.
I tested the truth of the frame sides with tight stringlines. To
check for twist, level the frame at one end and then place the
level at the other end to see if it will give the same reading.
Adjust with the jacks as needed.




first page the frame the floor the sides the roof the flooring the shell wiring and insulation sheet metal molding the hatch lid doors fenders light fixtures cabin cabinets solar panel tanks other stuff

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