I'm not familiar with the shock/spring setup on the Gen 2's, but what about using a airstrut type setup like a Shockwave? You could ride at stock height or slightly lowered, but be able to get maybe 3-4" when parked depending on frame clearance when suspension travel isn't an issue?
Looking at the pics of the Coppertone truck that was posted, the airstrut seems to be the way to go. Without having all the details on the parts they used, it looks like they only had to modify the top of the rear spring perch by cuttiing out the top and welding in a new mount for the shock assembly.
Also...Did you install the springs using the isolators!? I know that on some mustangs the isolators in the spring perch can make up for up to .5" sometimes!!
Looking forward to seeing the final product....thanks again for making this well needed mod!!!