Skip the tray. Only collects junk and sawdust. Better to leave space under the bench to clamp stuff to the bench from both sides. I also found that one bench with all around access was the most handy.
I have two vises on one end of one of my benches. That has proved to be very handy. I did put a leg bench on the front side. Hardly every use it. Wasn't worth the effort.
On the other bench I have one quick release vise on the right end. Don't see the need for another at this point.
Why not come up and look things over?