Project Size ($0) for cost-plus project

When working with a cost-plus contract (materials and labor), there is not necessarily a signed contract. often only invoices are issued.
As a result, the project size value remains at $0 for this type of project (as seen with Dave). He believes there should be a better solution than manually updating the contract value, especially since this directly impacts the Insights page. Maybe add a logic if contract value =$0, and invoice paid value is >$1, take invoice value as project size?