-Likely never done on an Econoline. I've had my eyes on the Eseries 4x4 game pretty intensely since 2013 and haven't seen one nor heard of any anecdotal evidence of an Eseries on Portals. Doesn't mean there isn't one out there...I'm often surprised what pops up on social media from time to time.
-If you haven't seen 74Weld and their portals for the Jeeps (and other applications), you should take a look. They have a video on their instagram of their jeep driving over 5 gallon buckets with room to spare... https://www.instagram.com/reel/CZ7O4..._web_copy_link
The thing that will be difficult to deal with on an Econoline is the extra width. Definitely some fender work to sort out.
-Never driven a portal axle rig but considering that the Mercedes G-class has portal axle options and most of those are not exactly full time off-roaders, I'd say that on-road characteristics are probably more than livable. 74Weld is going hard after the portal game for a number of rigs so I'm sure it can't affect things too much in a bad way if their target is a list of pretty mainstream vehicles.
I've inquired about built axles with portals through Emerald West (not more than a couple hours from me) and 1) They were horribly unresponsive to even basic questions over email....not to mention they never fully answered my no-so-basic questions 2) Never returned my calls. Left multiple messages and never got any call backs.