If Gary's suggestion doesn't work, phone your RO Supplier tell them what you're trying to do most will help. Failing that, phone one or two of the w/c Suppliers, they're all helpful, well most, tell them what you're trying to do and they'll either have an adapter in stock or know someone who has.
Windowcleaningwarehouse
Soapnational
Cleantech
Purefreedom
Gapswater
Just cross their palms with silver
And that's a good one too, Clearview.