Is this a big mistake? Carribbean for a year with the X-A2 27mm & 18mm, instead of 16-50mm

For a hot and humid environment at an upcoming vacation spot, I opted to get a used 18-55mm f/2.8-4.  But I HAD been looking for the 16-50 (also used) having decided that it was fine for daytime picture-taking.  It was just that an 18-55 came up for sale at a great price (a kit lens that the original owner hadn't been using).

The odd thing is, I'm STILL contemplating getting a 16-50 as a light, cheap and versatile travel lens for the simple reason that people have been selling it for such a bargain sometimes.   In daylight,  I'd be using it at f/8, where it'd be razor sharp for what I wanted to use it for (vacation).  If I damaged it, it wouldn't hurt me very much.  It's the same rationale I used to get the (also under-rated) XC 50-230mm.

I've been at a windy beach where a sudden gust of wind covered a Sony point-and-shoot with sand when I had the camera on and the lens consequently extended.  I immediately pulled the battery instead of turning it off so that the lens wouldn't retract and pull dirt into the body.  It was a royal pain to remove all the grains of sand without a proper blower brush.  In fact, I gave up, put the camera into a ziplock and waited until I got home to clean it.

The short of it being that the nice range of the 16-50 means you might not need to change lenses at all if shooting in the day--and that's very useful in a sandy environment.  Also, and you would know this, being the owner of both, the 16 end would be noticeably wider than your 18 and thus be more useful if there's sufficient light.  [The 16 end is also why, despite me owning the 18-55, I'm still thinking about getting the 16-50.]

tl;dr - keep the 18 and the 16-50 if you must bring only 2 lenses.

Related:  would you get enough for the 16-50 selling it used to even bother?  Around here, I've seen them advertised for approx $120 USD asking price.