Welcome to Mobileread Tim
I'll give this a try. Moon+ is perfect for my non-library books, but I'm still missing features for library books. Overdrive lets me turn pages with my arrow keys, but won't lock the screen orientation. Can't recall how customizable it is in terms of viewing options. Aldiko will lock the screen in portrait and is super customizable, but won't let me turn pages with my arrow keys (last time I checked at least). My attempts to convince Aldiko to add the arrow key option have been unsuccessful thus far.
I'd love to find an overdrive replacement that locks screen orientation, can turn pages with whatever button you like (or at least with the arrow keys), and allows me to custom set color and size and spacing and other visual options.