Some of my best ideas come when I am sleeping.
This morning I woke up and slapped my forehead, wondering why I didn't think about this earlier.
While installing the vise chop, I noticed that this vise has quite a bit of slop. The vise is well made, with stout parts and a good design. I did choose to go with the smaller of the two vises available, thinking I didn't need anything too big. I can't say whether the larger vise has this slop, as I haven't seen one installed this way in person yet.
You will notice that the vise is installed very near the front edge of the bench, but the chop reaches almost the entire width of the bench, leaving a fairly lopsided look when viewing from the end. Unfortunately I don't have a picture of this at the moment. This results in the chop leaning a bit to the right when it is open and no pressure is on it. The slop in the vise results in the right edge of the chop dipping down a considerable amount below the end of the bench. Probably about 3/8 of an inch.
When I installed the chop, I chose to line it up as best I could with the top of the bench, tighten the vise and then marking out the pilot holes. Now the vice lines up perfectly with the bench only with help.
The chop is now in the trunk of my car, as after I took this photo, I marked where the chop overhangs the bench, took it off and intended to cut it to length on a table saw at the Army's woodshop. The Army's tablesaw didn't give me confidence that this would make a clean cut, however, so my intention is now to make that cut with a handsaw. I just haven't done it yet.
Good thing, too, as I thought of a better way today. I am going to plug the holes in the chop from screwing it to the vise and try it again. This time, I am going to line it up adding the slop in the vise to the equation. I'll mark the pilot holes when the chop lines up while the vise is loose and leaning to the right. After I surface the top of the bench to make everything flat, including the tops of the vise chops, the end vise chop should stay flat to the bench because it is already leaning to the right. If I would have done that the way it is, every time I open the vise, the chop will droop to the right.
I'll let you know how it goes.