Andrew: Great diagram! Can you create some that would demonstrate the relationship of the torsion arm to the other 4 parts of the suspension. i.e. axle
tube, rubber, axle
, torsion arm and spindle?
Do some "reverse engineering" on your trailer. Check the specs for your year for the total height and headroom. That should give you some idea of how far the "kitchen floor" is off the ground. Compare your trailer to that. That should give you some idea of where you should sit.
Check the Dexter site and see if there is a distrubutor or manufacturer in your area. If not call the their customer service line to locate someone that knows their products.