Quoted from Nightstick:it looks awesome. well done. mine leaned to the right as well. I will have to try the 3m tape to the back. the problem is it does lean on the left ramp and the sticky bracket doesn't hold it for that long.
i used a small amount of automotive strip caulk on the top lip of the left ramp and set the tank in it , it is sticky and holds things in place great, works on lots of different things, good to have around.