Charter a boat for a week of the appropriate size and configuration. See how it feels after a week.
Without getting into a long post:
1. "Living aboard" in a marina in a temperate climate
at a dock with shore power, heat, air conditioning, access to fresh water, WiFi and/or cable, a pump out station and a vehicle is about the same as living in a small apartment.
2. Living aboard on a mooring ball or at anchor without shore power (no heat, no air conditioning, great care in the use of electricity, some days it will be too rough to take your dinghy to shore, great care in the use of water would be the next step.
3. Actually sailing the boat from place to place adds all the joy and fear of sailing - weather, running aground, etc.
4. Offshore coastal sailing - when you might get "caught out" in some bad weather if you are not careful is the next step.
5. "True" cruising (my words) - crossing oceans etc. is a world unto itself.
If you are willing to put up with a small space and occasional discomfort "1" above is pretty easy. Most boats are not insulated hence the comment about temperate climate - very hot or very cold and your HVAC will have difficult coping. Also I think you have to be an "outdoor" person. Bugs, mosquitoes, occasionally getting wet are all par for the course.
Hope this helps...
Fair winds and following seas