good choice. I tink the minimum size is 4'x2'. you'll be happier with 8x2. No need for the extra foot.
I sized my shelf under the bench so that rubbermain bins fit. Two on the floor, two on the shelf. With a 2x8 bench you can fit EIGHT rubber maid bins for storage of supplies.
Seven, after one space is eeked out for the tumbler and the media separator.