Discount or coupon that ONLY applies to products IN STOCK

Hi everyone, hopefully you can help me,

With Black Friday around the corner, we wish to apply a discount to all IN STOCK products on our website. Unfortunately every plugin that I find does not have the option to limit said discount to products in stock… (which seems strange as I feel it is quite a simple rule?)

All our products have “Manage Stock” active and accurately show stock levels. All we want is that if stock is zero (backorder, which is allowed) the discount does not apply…

We are happy for the discount to be automatic, or to be via coupons, whichever is the easiest solution to prevent discounts being applied to products on backorder, without having to manually include or exclude products in the discount…

Any help is greatly appreciated,
Many thanks! Martin

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