I am working on something similar. If you have any pictures of the truss, that would be great. Also, I am currently researching the geometry of the intersection points of the front landing gear tube and the strut tube (this intersection is an imaginary line drawn that intersects the 2 lines) to assure there are no buckling forces to the front tube under a hard landing. The geometry is important there. I will be happy to share my findings with you. If you have any drawings of your gear, I can check your gear for that as well.
I took my inspiration from the stock design (Dean is a genius), the Lowell Fitt gear (a much higher compression/tension application then stock) another similar bush gear design (with a spring that has a short compression stroke), and a gentleman that was experimenting with the poly bushings (they never bottom out). I think the 2 key things to be careful of are the angle between the swing arm tubing and the strut tubing as well as where the intersection of the imaginary continuation of the 2 arms would occur (somewhere near the tire bottom). This can be seen by taking a pencil and continuing the lines of the 2 components until they cross) First, If the angle between the arms get too narrow, the tension on the strut and compression on the front swing arm tube become too high. Second, if the intersection of the imaginary continuation of the arms cross at too far an unideal point, you can buckle the compression arm (the front gear tube). Because this intersection moves, when the gear is cycling, care needs to be take as to where you design in this intersection. This would be controlled by the angle of the front swing arm tube, where it welds to the axle tube, and the angle of the strut tube, and of course, where it swivels on the axle tube.
I like how you put use the fabric to move the air around the cabane. What is the vertical distance your cabane bracket (where the tension rods mount) hangs from your floor? It looks like many used 7-8 inches. It looks like 6" might be the closest one could get without too much tension on the longerons.
Dusty, I really like what you did here. You inspired me to start experimenting on my end. With that said, I need a starting place. I am looking to start with the Avid bush gear drawing, but substituting the urethane. A couple of questions: did you cut your urethane to 2"od and 1" id? Are you using 4 x 1.5" tall pucks with aluminum 2"od by 1" id washers? I am thinking of 8-10" height for mine. What size pipe and wall thicknesses are you using to fit inside the id of the urethane pucks? By the way, I personally prefer the Prothane lubricating grease. It is water resistant, plays real nice with urethane and metal, and provides a nice viscous friction damping feature.
This really has my attention. I like the "no spring bind" feature. I guess the trick will be figuring out the best durometer/length configuration. I have a MKIV with a Jab 2200. I am thinking 8-10" of 90A, but I am not certain yet. Anyone know more than I do on this?