Performance Insight - Different Currencies

Right now performance insight supports only $ USD and do all the calculations based on Opportunity Amount. 

We are supporting in Salesforce opportunities in multiple currencies - which is not reflected in Marketo's reporting suite. E.g. 1000 KRW = 1000 USD in Performance Insight which makes any metrics derivates from opportunity amount (pipeline, revenue, ROI...)

In our case we have a field in Salesforce which recalculates everything to USD. The correct value is available. 

Sounds like there would be minimum effort to allow us to remap from currently used "Opportunity Amount" field to "Opportunity Amount in USD". 

Or is there another solution? How do other global customers deal with multiple currencies?