A couple of points on this general subject to help understanding.

If you (individually) spend more than 183 days in any year (tax year in some states, calendar in others, 365 days in yet others) you become taxable in that country. This is not policed (recorded) in the EU as far as EU citizens are concerned. However, if local officials have reason to believe you're tax resident, it will be down to you to prove you're not (through airline tickets, ferry tickets, location of credit card transactions etc).

If you're taxable in a country, all your mobile capital goods items (cars, caravans, boats) that you use in that country should be registered locally - and may attract taxation in various forms.

Some countries additionally require that any mobile goods (cars etc) should be locally registered if they stay longer than 6 months, irrespective of your own taxable status. This is not policed, but the onus of proving a shorter stay will often lie on you.

For instance, Greek police sometimes check cars leaving on ferries, and ask when the car came in . . . and issue an on-the-spot fine if 6 months has been exceeded.

So, it's you, or your kit!