If you’re going to use a temp sensor to trigger a relay between the SCC and the battery, I’d be careful in the choice of a relay. I have a different Victron SCCs that charge at 15 amps, 30 amps, and 50 amps. I would need a relay that could work at DC amps. On one system I have three SCCs, a 50 amp and two 30 amps, so the temp sensor would need to trigger all three.
When I looked at doing this, some of the relays I looked at were not easily labeled for AC current, which is safer to work with then DC current. The DC relays I looked at were also more expensive than an AC counterpart.
Since I already had the VIctron BM-712 with external sensor and Victron Blue Tooth SCCs, I gave up my search and used the Victron Bluetooth to shut off the SCCs When it gets too cold. When I did that, I had to put the Victron Cutoff voltages above the Overkill BMS voltages so this would be primary.