Sorry to be harping on this rebound spring issue
Just realised, maybe the reason against shorter rebound springs is the risk of bumping on extension (as the tire goes into a hole).
The solution is maybe not a shorter rebound spring but a shorter (softer) main spring that sags just enough in static condition to keep the preload off the rebound. Shortened upper springs to give 1" lowered ride height in combination with with standard rebound springs might give this. Standard length upper springs plus the bearings probably result in preload on the rebounds. Unless someone can give you the exact details it will be a case of trial and (hopefully no) error.
Cheers J
