Multiple WIP accounts with Progress Billing

In the construction edition using Progress Billing is there a work around to use multiple WIP accounts?  We currently set up our projects with multiple costs codes using different account groups to each Task.  We want to use WIP for proper accounting, however the issues lies when we go to invoice a project task we can only select 1 WIP account group to apply reversing transactions.  This means all of our project transactions (material, labor, other) must be grouped in to a single WIP account to ensure all these transactions are reversed upon invoicing.  We then loose transparency of the project costing having only a single costing account to view until invoiced.  This doesn’t seem to be a problem using Time and Material billing method, because we don’t have to select a single WIP account on the project task.