I don't put water in mine, it just accumulates from the mop.
I think I might go with a slimmer mop sleeve and maybe cut the mop handle aperture down on my old bob, so the mop sits lower, and then maybe make a blanking plate to fill the LH mop aperture. If that works then I may cannibalise a new BoB.
If that fails, could be an unger classic with a thinner mop sleeve.
Do any of these BoB companies field test their products...?