Water table size question

For those of you that have water tables, what size did make them? Here's my dilemma... I have a 4x8 sheet of 1/8" steel and some 6"x 8' strips of 1/8" steel I could easily weld up a 4x8 water pan but then I wouldn't be able to cut past the edge of a 4x8 sheet of material. If I angle the sides out it makes mounting the slats that will support the work piece a bit more tricky. I could weld a 1" or 2" strip along the bottom edges to widen the 4x8 sheet by an inch or so but that's a long weld bead and it might warp the bottom plate. Am I over thinking this? Thoughts?

You've got it easy w/ a 4x8' table. Just buy a 5x10' sheet, cut to 5x9', notch the corners 5", bend the sides up and weld the corners.