I assume there is a handy reason to have a 1/16th scale for tiled maps (perhaps for doing computations on which tile is being hit or changing tiles (they're at handy whole-number indices).
Anyway, regardless of what transformation (and thus what "camera" and thus what projection matrix) is used for rendering your tiles, you can use a different camera for your UI.
Look at the Superjumper demo, and see it uses a separate "guiCam" to render the "GUI" elements (pause button, game over text, etc). The WorldRenderer
has its own camera that uses world-space coordinates to update and display the world.
This way you can use the appropriate coordinates for each aspect of your display.