Billing Rates by Earning Types

Hello,

I have a client using Acumatica payroll and Construction. The client also has Union payroll. On T&M billed projects, they bill labor dependent on the 3 below items:

1. Labor item (Journeyman, Foreman, General Foreman)
2. Earning Type (RG, OT, DT)
3. Union (SheetMetal, Carpenters, etc)

The current Rate Tables in Acumatica only go as far as Inventory item. I know I could create a non-stock item for each rate type and union, but that’s not feasible for this client.

I have created a very long IIF statement in the billing rule that works but it’s too long, the system cuts it off after 4000 characters.
 

Is there a way to create a Rate table based off of these 3 items that I’m not seeing?