I don't have any information on a factory tray, but we did fabricate one of our own design for mine.
Tray pic 1, tray pic 2, tray pic 3. The whole thing is mounted to the floor with 4 1/4-20 bolts. We sized it to be about 1" wider than the tank, with about 1" clearance above the line coming out of the top of the tank.
