For NEC and probably local permit approval, you'll need Rapid Shutdown for your PV panels. The Sol-Ark has a RSD 12v signal which, if you wire it to the RSD module brain, will shut down the modules when the Sol-Ark is shut down. If you move the 30A Sol-Ark breaker into the garage panel you'll need to make sure the panel's main breaker and panel is sized accordingly, there are rules for downsizing the panel's breaker when you feed a Grid Tied inverter to it. Right now you have what is called a load side or supply side tap. Anyway, I personally haven't put 2 wires in a CT but my minimal google research shows it is done and works and sums all the current as long as the wires are the same phase. It's certainly easy to just do it and see if it solves your problem would would be very simple. Another possibility is to remove the 30A Sol-Ark breaker and use a tap to the mains. These are UL approved devices that clamp onto the wire and cut into it, and then run the #8 wire (or whatever is feeding the sol-ark) directly to the Sol-Ark, like a Y connector. The Sol-Ark has a 60A breaker / disconnect in it on the Grid input/output. However, simplest solution is to try the 2 wire inside 1 CT. Just turn off the main breaker and measure there is no power present before messing with stuff in there.
I tried this, and it seems to be working, but with one caveat. I wrapped each CT around 1 wire from the 100a breaker and 1 wire from the 30a breaker (one CT for the leftmost wires and the other for the rightmost). I then enabled Limited To Home and TOU, and the Sol-Ark is indeed drawing from the batteries right now and not the grid. I even tested with charging the EV for a minute, and the Sol-Ark drew from the battery up to the limit I had set, and the rest from the grid. The weird load loop didn't happen, but the Sol-Ark does seem to be drawing twice as much from the battery as is needed i.e. the home is using ~200w right now, and the Sol-Ark is drawing about 410w from the battery. The AC just came on for a bit, and the Sol-Ark drew 2.4kw from the battery when the home was only drawing 1.2kw.
Anyway, definitely a positive step, as atm at least, it seems to be working. I'll see how it's doing later tonight, as well as tomorrow morning. Many thanks for this very interesting idea!