I don't recommend singing from books. Or notes. Or computers. I would point out, though, that my newly-acquired (now out-of-production) Toshiba Libretto is physically a good bit smaller than RUS, weighs about seven ounces more and currently carries about sevet times as many songs.
To make an almost-perfect songbook (for you, anyway---I might hate it) why not fire up the old printer and make your own. DigiTrad is a good source to start with; there are, of course, others.