Forecast excl estimates in KPI Scorecard

Hi,

I need to add a KPI to our scorecard for our salesreps that is the equivalent of forecast excluding estimates. I know that I can exclude the estimates from forecast through the accounting setting. However I do need the estimates to be included most of the time.

I can of course create custom reports that filter the forecast to exclude estimates but our sales reps need to know the forecast for expected billing from sales orders + billings at their dashboard.
And I can't add a custom reports to the KPI Scorecard for some strange reason.

Any tips?

(note: we use the advanced billing feature, so one sales order can generate a forecast for over a year)