The new yankee workshop table (I was only suggesting the top, not the legs) is a torsion box, with a lot less support (and less work) than some of them.
You could make it in several pieces, and try to connect them with bolts, clamps, or have a slot that fits a piece of wood to align them.
It sounds like you want something that’s 9’x5′, so maybe three 3’x5′ torsion boxes, or two 4.5’x5′ boxes. That would definitely make it easier to store. It would also make it easier to cover since you won’t find a piece of 9’x5′ plywood.
I like the design of these: http://www.woodmagazine.com/woodworking-plans/woodshop-projects/saw-horses Although it’s difficult to match the strength of a standard saw horse. Especially if you recess the legs into the top with a dado. The strength usually goes out the window when you make them foldable though.
The thing about the torsion box is, you have to have a table saw. You can’t make the cuts accurately enough with a circular saw, at least I’ve never been able to.