Twgriff1 has the right idea. I don't want to beat a dead horse, but when I built my 6 ft "Stacker" teardrop, I weighed the wood body, and it came to 95 lbs! I also weighed the 4 x 8 ft HF trailer and it came in at 150 lbs. I feel the elimination of twisting and racking of a teardrop trailer is attained by a sound floor, sides and roof, NOT by a heavy, welded metal trailer frame. (I have tested this idea by jacking up just one corner of my teardrop with the tire 6" off of the ground, and have noticed no binding of the entry doors)
Therefore, thinking as an "old" woodworker, I feel that a soundly built wooden body, bolted solidly to a simple angle iron at the floor-to-wall connection is all that is needed to attach some torsion axles. No trailer frame, long axle, springs, shackles needed. A lengthy steel tongue bolted solidly, the full length of the teardrop body is all that is needed. I know that some die-hards feel differently, but having built such a cargo trailer, 55 years ago, it worked just fine hauling my worldly belongings 2500 miles down route 66, while California bound.
However, if building light is your ideal camping unit, you might consider a hollow-core door for the floor (as I did) and keep the thickness of the plywood at a minimum...... That's my story, and I'm sticking to it.

Roly