Shakedown cruise question

Just in case I am assuming (assume...makes an "ass" out of "u" and "me") incorrectly...and it is my first outing...and I am a smidgen apprehensive about screwing up... I am posing this question that probably does not need to be asked, but here goes. 

I just picked up my new R-Pod 178 and parked it at my house a little over a week ago. I have been diligently trying to learn all that there is to know about it's operation (especially winterizing and dewinterizing which I plan on doing myself). It came from the dealer winterized and I have not added water to the system. Living in southern Oregon we are at the time of the year where I would need to re-winterize if I did use the city and/or on board water supply.  

So here is the question. My wife and I have decided for the fun of it...and as kind of a simple and easy preliminary shakedown cruise... to drive about 5 or 6 miles away to a local RV campground (it is open with full hook-ups) and spend the night and then come back home the next day. I plan on NOT hooking up to the city water hook-up or adding any water to the fresh water tank. But...I thought we would use the sink drain to dump some gray water and other appropriate liquids we might want to dispose of via the sink. 

I am thinking that all I will have to do before returning home and storing the pod in the winter weather is simply dump the gray water (there shouldn't be but 2 or 3 gallons at most), pour a cup or so of pink antifreeze down the drain for the p-trap, and that will be all that is necessary....correct? It seems that all wintering and dewinterizing information I have seen simply says to empty the tanks (black and gray) and I assume that because of the size of the tanks vs the small amount of liquids/moisture left after dumping that freezing temperatures will not adversely affect either black or gray tanks (as mentioned though our black tank is not going to be used this trip). 

Is that correct or is there something I am missing? I am leaving this afternoon and would like to feel just a little more comfortable when I return to the subfreezing weather to park my pod later tomorrow that I haven't missed anything in this regard.

John