Hi Bodie,
With invoice.create you can include gateway information to ensure that PayPal Business Payments is the selected gateway, but I'm afraid recurring.create still only accepts gateway info to be used in an auto-billing situation. Since Business Payments isn't an auto-bill capable gateway you still can't specify it when creating a recurring profile via the API.
I can definitely bring this up with the API team again, but I can't make you any promises.
For now it looks like you may be stuck doing something like setting up a webhook for invoice.create and then doing an invoice.update call as soon as a profile generates an invoice, adding in Business Payments as the selected payment option.
Hope this helps. :)
Nox Dineen | FreshBooks