New tubing set up for filling the water tray without opening the bator door.
Got a bunch of super useful medical supplies from a closing down vet office of Ebay a few years ago (Literally paid about $30 for several thousands $ worth of stuff).
This is made up of 2 IV extensions with a three way tap. One end will go into the outside resevoir of water, and one into the water tray. Use the 60ml syringe to suck up water from the resevoir and the 3 way tap to direct it into the tray.