Lots of European countries are more relaxed about nudity. Barcelona has some nude beaches (such as Mar Bella) that are right in between other beaches, easy to get to, with lifeguards, first aid, toilets, two beach cafes (one called chiringuito BeGay), an indoors restaurant, a childrens play area, and most of it within easy view of (being just off) the walking/riding path. People wash off the sand and seawater nude at showers next to the main walking/riding path). Even at beaches not designated as nude, people are casual about stripping naked to change.

I've been to several gyms in German cities and was a bit amused that signs require wearing bathing suits in the pool and on the pool deck, but demand nudity in the sauna area (including walkways, decks, steam rooms, saunas, hot tubs, etc.), which is mixed gender. In Munich people widely go naked in the main park and along the river. I admit I was a bit surprised when I rounded a corner and came onto a 250lb German man grilling sausages for his family in the park.

So I suppose it's reasonable no one would think it unusual to change naked at one's seat, or to take offense at it.