If you elevated the unit high enough & attached a flexible small diameter (similar to a coiled air hose) always draining down except when door is open) , seems like you wouldn't have to detach it to open the door . Of course there should also be a simple way to rig a weight actuated pivoting spout unattached to the door, to dump into the door exit & then pivot back towards the unit . You know , like the old steam locomotive watering stations .
Outer door exit would have to be screened .
I love these mind challenges , but that's what I did for a living !