@MELGAR posted:Peter,
I recommend additional lower bracing (left to right in your two photos above). Mianne doesn't suggest this but I think it makes the table more sturdy and rigid. I have included it on both my layouts. You can see what I mean in this photograph of my 10'-by-5' layout table. I prefer legs to be braced in two directions. Just a suggestion and my personal preference... You can add it later.
Edit: As far as tabletop overhang, you can see that my layout has been built with 6-inch overhang on each side. Table plywood is 1/2-inch thick. Hasn't caused any problems at all, but I don't stand on the table.
MELGAR
I see what you mean....I have a few leftover 48" I-beams and I intend on using them....thanks, Mel!
Peter