Timmeh, i have that switch just the 12V version. It's connected but just the power side. I think to use it as a second level of protection (type 5) if anything goes wrong. I took some pictures inside before mount it.
Just checked i have 7700 model and beside the slightly different label i can't find other difference.
Also in the manual you attached there is no 'Remote control switch current'. In mine it says <100mA. So if assume that you have the same you'll need an external SSRelay capable of that current as SBMS0 IOs are only 50mA.
This is half of the equation. As its controlled by a two button push switch i'm not sure (have not tested)it can stay long time with the on or off signal applayed.
I know for sure that there is a switch inside to turn on the led inside the push button and its wired outside. I would connect the off signal cable in series with that switch so when the relay is off the control wire (for off switching only) is disconnected too.
What will be you using that relay for exactly? If it's just for Low Voltage disconnect the Victron Smart Battery Protect is a better choice as it's solid state relay. And its in 65, 100 and 220A versions.