The owner’s policy does nothing for you
Their homeowners or landlord policy covers their building and their liability. Your belongings, your liability and your cost of living elsewhere after a loss are entirely yours, exactly as in an apartment. The informality of the arrangement changes nothing about that.
Shared space raises shared questions
A shared driveway, pool or garden means your guests are on property you do not control and the owner’s guests are near where you live. Where responsibility sits in an incident is less obvious than in a separate building, which is an argument for carrying a sensible liability limit rather than a minimum.
A handshake tenancy still benefits from writing
Many of these arrangements have no formal lease. A short written agreement covering rent, utilities, access and notice protects both sides, and it also makes any claim considerably simpler to settle.