Nude SUP (stand up paddling)or better SOP (sit on paddling)

This year my wife and me, we have bought two SUP-boards. And now, we are often paddling on the lake "Lauerzersee" and "Zugersee" in Switzerland. I enjoy the tours naked, my wife prefers to be clothed.
(One pic in media)
Why SOP and not SUP?
Since I have had balance problems for a few years, standing on the SUP is impossible for me. That's why I'm always on the board.