Pit Optimization Different Metal Product Payability

I've recently started looking at a couple of open pit projects with oxide/weathered and sulphide domains that would produce two different products for the same elements which have different payability. 

For example Cu oxide material type that would go to leach and electowining process and produce a Cu cathode; and sulphide that would float make a concentrate. Or Au in an oxide that would leach and produce dore and Au in sulphide that would float to a bulk sulphide conc.

Within the customers tab of the PO it is only possible to specify the selling price of an element, not the product, the product is dependant on the processing facilty which we can define by material type. 

So for example if we were producing a Cu cathode from Material type OXIDE, which went to process LEACH and we could sell that for 99% of the the spot price of $6500/t AND we have Material type SULPHIDE going to FLOAT which would produce a concentrate, where we would expect to be paid say 85% of the spot price.

What would be the best way to handle this in the pit optimization? We could apply a selling cost to the different processes, but this wouldn't be taken into account when running nested pits with RAF.

Another option would be to make two extra columns in the BM, one for Cu_Oxide grade and another for Cu_Sulphide grade and treat these as two different elements with two different prices. 

Any suggestions welcome.