This one is on the tip of my tongue... a recently married couple is embarking on their honeymoon along with their children from a prior marriage. While on the trip, their boat travels through a fog bank in the Bermuda Triangle and they wake up in the wrong bodies, with the parents having swapped with their kids with some disquieting bits involving both sides getting confused about what is or is not acceptable about opposite-sex relations when the age of one's mind does not match the age of one's body.
Eventually, the boat reaches land, after the trip through the Bermuda Triangle. While they initially thought they'd only gotten displaced in time and space, it turns out they're actually in an alternate Earth that operates in reverse order than their original Earth, and is peopled by people who have disappeared in the Bermuda Triangle with the "past" arrivals actually being from the protagonists' future, which featured a lot of civil unrest and breakdown of nations. Therefore, what remains is a very Libertarian society with a slight bias towards people from the region of Israel (something to do with them having been majority survivors after a war before they got caught in the Bermuda Triangle effect).
I am pretty sure I read it in the last five years (somewhere in the 2012-2017 timeframe) and I think it was as an eBook, not a physical one. I was mainly struck by the thoughtful exploration of what happens when a Freaky Friday switch doesn't get resolved, but it also seemed well-written, although I remember the last bit starting to feel a lot like the author was more interested in describing how this alternate society was superior to ours in so many sociopolitical ways.