What's to figure about Schengen limits?
The simplest excuse if the most likely. Or, as the journalists used to say, follow the money
So Reason #1 for a 90 day limit, is that the average traveler will be flying in. Having a 90 day limit ensures they need to book multiple trips, pay multiple airfares, make the state-owned airlines more profitable. Easy enough.
Reason #2 could be simple political vengeance, reciprocity. If the US was issuing 90-day visas to some Schengen zone citizens...slap! slap! Here's right back at you, you get the same shabby treatment.
SOMEONE set those limits for a reason, and in one way or another it was probably designed to either penalize or profiteer.
You can try to dodge it--but penalties at border crossings everywhere have always been somewhat arbitrary and subject to mordida. As long as you're willing to be physically ejected and have your boat separately arrested in a foreign port, no problem. Or you can fly under the radar
and maybe avoid that.
Simpler to get out of Schengen, find a world-class accommodation in Tunisia
, Lebanon, Croatia...You know, just deal with it and don't worry about overstaying.
Then you can also write the first "World Cruisers' Guide to Dancing Around the Schengen Zone" and become a famous (and well appreciated) author at the same time.(G)