We primarily use Andersen windows and have found that by making the R.O. in the SIP overlap the frame by an inch you can get the frame to effectively trim out the window. Look closely at the window manufacturer's head, jamb, and sill details to understand the relationship between their R.O. and their "unit dimension" and then see if you can get a handle on the window frame cofiguration and sizes. Most manufacturers provide scaled details in their catalogs. Good luck, if you pull it off it can look really sharp!
