I spent the last couple days relocating my original water bed... note to self: next time, don't put it in front of a door you want to be able to use at some point, and for crying out loud, never again make one that's 8x8 unless it will NEVER move.
I'm thinking that 4x8 is a good size, or maybe even 2x8. It gets challenging when you want to check on plants that are in pots in the center or far back, if your bed is too big. Unlike dirt beds, you can't just walk between the pots, unless you like wet shoes.
Anyway... once I got it relocated and re-settled, I took the 8 bare-root DLs that I brought home from our last club meeting and put them in the water as well, This is going to be a very handy summertime holding area for me when I bring home new plants, I think, And if I again wind up with DLs that didn't make it into the ground before winter, I know that they can safely overwinter in my driveway.