Is there a way to allow access to a secure portal/AGSOL G5 workflow in a site/viewer using a Portal identity that would persist even when end users login to viewer with windows authentication - not an ArcGIS identity?

Is there any way of using on premise G5 workflows shared only with my Portal organization (not shared with everyone) in an html5 viewer with users setup to use their Active Directory login credentials to sign in to the viewer, not Portal identities? We're trying to limit the need for all users in our organization to have a Portal identity as well as a windows account. I understand you can set up Portal/AGSOL to use active directory logins but this is both extremely limiting (required windows password changes etc... ) and has IT security concerns.

Thanks,

James