You're missing the problem. It's that they lose the unemployment by coming back to work. Even if they were paying (any reasonable definition of living wage plus hazard pay), the unemployment payment structure still disincentivizes them.
It means their pay would have to be some $600 over and above the regular amounted needed to compensate for the inconvenience and utility of work. So they're effectively "taxed" at over 100%. At that point, it's not the employer's fault for not offering enough.
At the very least, they could just make it so that unemployment (i.e. same logic as behind the UBI -- have social benefits, but don't [significantly] contract them as you work more).
"I can't get my employees to come back because that would mean they would be making less money. I can't envision any solution to this problem"
If an employer wants employees to risk their lives as the quarantine lifts and the second wave continues to spread, they need to offer more money.