I agree, yours is an elegant solution to the problem you faced.
It actually allows an additional mod. that the standard vice does not - you now have the strength in the vice base to tap a series of holes to fit the studs from your milling step-clamp set, so you can clamp irregular shaped objects directly to the vice table.? This is esp. handy for cutting angles >45deg or mitering work too wide for the std vice opening, if you remove the movable vice jaw.? The std vice base is too thin and the cast iron too weak to do this - jv
John Vreede