I too have a set of attitude goggles. No one seems to have an answer but from what I know, because the Fatshark runs on 5.8ghz and so does the P2V, having two 5.8 ghz signals on the same system would cause signal interference and not work.
Try asking the DJI Guys on Youtube. They experiment a lot.
Is not so much FPV (just the vision appview) but cant you output the phone/tablet display to HDMI via MHL and then use that feed into the new Fatsharks that take HD input ?? (just wondering)
My problme is that I just cant see my iphone well in the bright light condtions that the Vision likes. So I was thingking the same thing - take and output from the iphone and feed it to the goggles. I'm not sure how you'd work the controls on the phone, howver.