sounds like the old Boxster "little red clip" would solve your problems similarly and allow windows to dip slightly when top is being raised / lowered.
Two reasons (among many I'm sure) most cabs dip windows is to:
- prevent any undo pressure on windows while top opens/closes
- ensure windows seat properly into top seal/channel once closed
Shouldn't be issues w you manually raising/lowering but suggest you still dip thwindows a few inches before opening or closing..
Regardless, glad you were able to resolve issue - nice job