It sounds like a Tolino Vision 4 HD would work. It doesn't have page turn buttons, but you can tap the back to turn pages (they call it tap2flip) — and it has everything else on you wish list. Light (slightly lighter than the Voyage), small (almost the exact same size as the Voyage, but a bit thicker – 8.1mm instead of 7.6mm), waterproof, flush screen, has the color changing screen. Disadvantage is that it is tied to European bookstores, so you would have to use ADE or Calibre (with plugins) to get your books. (Has no issues downloading from places like Feedbooks, etc.)
https://mytolino.com/tolino-vision-4hd/ebook-reader/
It can purchased from a German store with free shipping to the U.S.
https://www.playthek.com/tolino-visi..._medium=artist
Currently on sale.
Should also mention that it has simple (minimalist) interface. (I like my Tolino i/f, but others may not.) And your dictionary won't match the quality of the Kindle's Oxford dictionary.
Another advantage over many (most) eReaders. You can download borrowed ePub Overdrive books directly to the Tolino (it has ADE built-in).