Hi there, @rachel.

For now, there's no specific feature available yet to track commission in the Project Center. 

Although, the commission item is already supported in QuickBooks Online Payroll.

You can see this link for more details: Supported pay types and deductions explained.

In the meantime, I recommend continuing the workaround that you're using to track or add the commission for the job.

The only item or transaction that links between Projects and Payroll is time entry. This is the only available option for now that we can use to map to commission pay on their paycheck.

In addition, there are several payroll reports you can use to view useful information about your business and employees. You can check them out by clicking this link here. 

I'm always here to help if you have any other concerns or questions. Just tag my name in the comment section and I'll get back to you as soon as I can.