I couldn't get one to work when I did that shallow long tank from an IH truck. IIRC it had 9 inches to work with and was close, but still no go after cutting the spring loaded posts down. Unless you can find a shorter bucket?

The pumps without a return line that come on newer rigs ar PWM and have PCM controls. Would be a sweet setup if that one did have a regulator in pump.

But if it's not designed to be returnless it's got to be a heavy burdon on pump designed to flow freely, without flow it would built up heat and without flow not cool?