Trend calculation that ignores date slicer

Hi - I have the following formula that calculates rolling sales based on the latest three months - I then use this to calculate trends:

Trend Test = CALCULATE([Total Sales.],(DATESBETWEEN(Dates[Date],MAX('Sales Data'[Date Value])-84,MAX('Sales Data'[Date Value]))))

I have a date slicer attached to the table for various other calcs in the same table and want to keep this. My problem is that when I move my dates into the future to look at forecast I can no longer see the latest rolling sales because I am in a date period for which we have no sales - I need a way in the above formula of saying ‘ignore the date slicer, just look at the latest three months in sales data table’

I don’t want to edit interaction because it causes issues in other parts of my table - hoping there is some way of using ALL or ALLEXCEPT to counteract the slicer in the above formula??

Is there any reason why you couldn’t just use time intelligence to project these results forward.

Here’s an exact example of how to do this.

It feels like this would work?