Reguardless of the rollball location, most will as least be installed so they fit under the hard top, so there's one standard/common.
Next one, is all must mount on the windshield frame in some fashion, 2nd standard/common with all applications.
This would be the starting point anyway. From there it seems to be only a matter of length and tie down strap locations...right?
Is making a different length all that difficult? Call it an "option" and charge accordingly for the extra material used.
Just thinking out loud...offering some possibilities.
