You need to fashion a cover for the access hole where the low point drains (grey pipe) protrude. Without it you'll get lots of road dust up inside. Additionally, the main tank plug and lots of plumbing is exposed to cold freezing air in the winter. It will freeze you plumbing quickly without. Insulate it with 1" styrofoam board. You can see the outline from where it once was.
While your doing work there, replace the white drain pet cock, and tubing to the tank, these are crap and prone to seizing and cracking at the worst of times! Ace hardware has a brass replacement for 6$ with identical centers and specs.