It would be a good idea to cover it. You don't want an electrical unit left out in the rain. If you don't get a cover for it you might use a large commercial trash bag.
Also, the unit will start smoking within the first hour. This is the machine oils burning off. (It isn't TBS :). That is the reason you want the water tray left in without water. It will burn off any oils on the pan also. Just a further note. When you get ready to smoke some food in the unit, you need to foil the drip pan and the pan in the bottom of the unit. It will aide in the clean up process. What I recommend is to place sand in the water tray and top it off with foil. I have found that the sand will hold the heat of the unit better than the water. Also, if you use water in the pan, when you open the door, water will run down the inside of the door and possibly drip onto your deck. If the deck is concrete or pavers, like in my case, clean up can be a real problem.
Thanks for posting and looking forward to some Q-View.
WC