Whatever you do- practice with each combination of clothing, coat, and holster. It's not always as simple as just adding a coat.
Luckily for me, I usually carry IWB, under an untucked shirt year-round. The mechanics of a wintertime draw are similar to how it works with most coats I use.
I have several coats that I use depending on- how cold it is, wind, rain, dressed up, dressed down, etc. Most have their own advantages or disadvantages for carry. The shape, length, material, and more, matter.
You will notice all the little things.
One may cover the gun well, but not clear it easily to draw.
Some "swing" open easier than I can push them back, like I usually do.
The lining of one may catch on the thumb safety, and move it.
Long coats may hide the gun better if you will bend over a lot. That one is obvious. But if you will be reaching up high, thay are nice then also. When you reach, your coat raises, possibly exposing the gun then also. When grocery shopping, I find that I'm getting things from bottom shelves, top shelves, and in between. A long coat is nice there.
But long coats are a pain if you spend much time sitting down while wearing it. You will probably be sitting on it, and that will make it hard to open it to access the gun.
If you won't be bending or reaching much, a shorter jacket-length works well. I try to avoid elastic waists on them, as that can pull the coat's bottom in the way of the grip.
Snaps can work better than zippers sometimes. You can leave a couple of snaps open to provide access to draw. Be careful- they can get "re-snapped" on you.
Longer coats often have the zipper than can open from the bottom as well as the top. You can zip the bottom one up to allow gun access, but the zipper will creep down.
I know a lot of that may not apply to the SmartCarry, but the point is- You may have to try out a lot of coat/holster combos to find something that works for you.