Okay, I guess I'll figure out how to add some kind of slotted dropout to a cheap used fork, with no front brake during testing. Once I'm sure of the optimum rake, I'll get triple tree clamps CNC machined with the correct forward offset then install untapered 1" 4130 tubing as straight fork blades, welded to Wright-style dropouts. Those tubes should be plenty strong to resist disk brake forces, and easy to align since there's no bending involved to create rake.