I haven't done this myself but you should check out Winneowners' sister site, specializing in van conversions, both Sportsmobile and DIY conversions:
https://www.sportsmobileforum.com/forums/
They have a lot of threads regarding aftermarket seat upgrades to Ford vans. You'll have to focus on driver/passenger seat upgrades. Here are the results of a Google search:
https://www.google.com/search?q=driv...hrome&ie=UTF-8
One thing you'll need to do is educate yourself as to compatibility. Your's is newer than most of the vans addressed on the Sportsmobile forum, but if you focus on vendors you should find what you want.
I believe you can join Sportsmobile using your Winnieowners login. You can then post your own thread.
Here's a link to one popular, but expensive, vendor:
scheel-mann usa | Orthopedic Automotive Seats