Filtered threshold slicer

Hi,

I know this is easy with the filters pane, but a corporate decision not to use that limits me here:

I am massively oversimplifying my data for the purposes of explanation... I have the following tables:

Sales - a list of sales (assume 1 row = 1 sale for 1 product)

Returns - a list of returns

Product - joined to Sales and returns

Dates - joined to Sales and Returns based on date of sale and date of return.

I have a slicer for dates and 3 measures,

Sales Count = COUNTROWS(Sales) 

Return Count = COUNTROWS(Returns) 

Return Rate = DIVIDE([Sales Count], [Return Count])

which are filtered by the date slicer, and shown on a bar chart, by product.

I want to add a slicer which allows me to set a minimum threshehold for sales, so for example any product with only 5 sales lines will be excluded. But I can't use a slicer based on the Sales Count because you can't have a slicer based on a measure.

I've tried adding a column on the Product table: COUNTROWS(RELATEDTABLE([Sales])) and then used that as "Greater Than or Equal To" range Slicer, but this then ignores the date slicer and I need it to be filtered to the dates.

How can I accomplish this?