What I’ve done in the past on other machines is use a relay to control the heated bed via a different power supply.
Main power supply powers everything except the heated bed, and the heated bed ON command is redirected to a relay coil.
The relay closes a contact that turns on the heated bed from a different power supply.
Please enjoy MSPAINT-CAD
In my previous case, the bed heater is a 120V mains powered silicone heater. I’m considering ordering something like this for the SM2: https://amazon.com/dp/B07FB1TZ25
But the inability to run a M303 PID autotune makes it more difficult to tune - you’d have to measure the Ku and Tu yourself.