From 1989 to 2004.... 6 months each in two locations.
Illinois campground... 400sf park model 400sf add-a-room 400sf deck 2 strorage sheds.
Florida over 55 retirement community... 1000sf mfg home with storage shed.
Totally comfortable for both, and made our downsize from 2200sf home easy. 700sf w/o extra storage might have been a little bit too small for us. without some extra private space, togetherness might be a question mark.
Location makes up for size... both homes on or next to lake.
Price was important to us total for both homes under $100K, so a different reason for owning.
Re cliff erosion... BIL and SIL had a beautiful 3000sf oceanview home near Plymouth on the top of an ocean cliff, back in 1974, about 40 ft from cliff edge. Both their home and the house next door were victims of erosion and are no longer there (circa 2002). As they say... "Location, Location, ...ulp gone!"
Looking at the Real Estate page for the house, found the "Big Lagoon" company... an interesting concept: