My original set up with a 16x20 GW washer was on a stand which I built from 2x2's, standing next to the tub, but the bottom of the tank was higher than the tub edge. The hoses will drain into the tub fine with this setup, but if I was to advise someone else, I would say if you could put the tank in a tray (like a 16x20), you'd be safer.
My tanks actually sit on the counter next to the darkroom sink, and drain into it, never a problem in 18 years.
If the bottom of the tank is below the sink, or tub, or whatever, the bottom drain hose will have to rise up over the sink to go into it, and I don't know how well this will work, but it doesn't strike me as a good idea. At some point there won't be enough gravity pull to drain it (like maybe when the water level in the tank is at the highest level of the drain hose.)
I would just make the cart high enough to clear the edge of the sink. Also, when you stop feeding water, disconnect the feed hose from the source, and place it in the sink. The tank will drain almost, but not completely from this hose and the normal drain hose. My tank is almost never totally dry.
Just be sure if there are kids around that you keep an eye on things.