Dave, I think she already pointed out she only has one area where she can even turn around in the sunroom, so with her wheelchair necessities, that's out.
Koshki, I think you were asking about circulation if you bring the fish into your garage for the winter. The answer is yes, some sort of circulation and/or filtration. If you just have filtration, you will also have circulation, is what I mean by that. It can be primitive, just something deep enough and enough gallons for the fish to make it through the winter easily.
What everyone on here says and I repeat, the bigger you go, the easier it is to take care of. I know that doesn't make sense in a way, but it's true. If you go bigger next year, and make sure you have adequate filtration, the pond will pretty much take care of itself for most of the summer. I don't do much to mine after spring clean out of any accumulated muck that may have gathered on the bottom of my ponds during the winter.
I didn't realize you had 18" of depth in one area, but still that's just not enough. If you were in a warmer climate, you would have cooked your fish during the summer.
It's not just for winter they need the depth. And, the fact you've already had a raccoon or some predator relieve you of your fishes in the past, that's yet another reason to go deeper. If you have straight down sides, it makes it VERY difficult for most predators to get the fish.
So, get yourself some type of a tote or large muck bucket or something big enough for the fish to stay in during the winter in your garage. As long as it doesn't freeze, and sounds like it won't, they will be fine. Just give them some filtration and feed very little. Not sure how they will handle things in there with no food at all, so if the water is warmer in there for now, you might get away with feeding them a while longer. Someone else that keeps fish inside for the winter can chime in here as to feed requirements.
Good luck!!!