Yes, 90-day reporting makes no sense. I am also a 3 hr drive from my nearest immigration office, so a full day, ferry crossing, city traffic, with costs of car

Yes, 90-day reporting makes no sense. I am also a 3 hr drive from my nearest immigration office, so a full day, ferry crossing, city traffic, with costs of car rental & gas. There's no fee for the 90-day renewal, so no opportunity for expecting a bribe - unlike so many other aspects of Thai immigration, where chance of a bribe seems to guide policy, and obfuscation of those policies. So the 90-day renewal does not even enrich govt, or (more importantly :) its immi officers. It is just an unjustified nuisance to all participants. And you need an exit visa if you plan to leave the country before the 90 days and then re-enter. Also unnecessary, because you will transit immigration at the border anyway - unless you are sailing out on your private yacht :)