We fitted one of those to a jet drive RIB but it's just a T piece with a one way valve so that the water doesn't go straight out of the back, you could make your own with a T piece if you turn the intake off I suppose, you would still need to seal the hosepipe end as well when in normal use.
A bucket is still easier!
British Champions! RIB Formula 1 2005
National Speed Record Holder at 90.15 (still)