I don't know if it's a "loophole," but I find my phone to be a pretty good eReader. I did the same with an old tablet (just has the eReader and the book(s)). I've never had a real eReader so I can't really comment on the difference, but if you're just trying to read, a good app costs a couple bucks, way cheaper.
Not that I've noticed. I can usually fiddle with the settings (some even let you program a day and night mode). But I also state at screens all day, so take my opinion with a grain of salt.