Hi Ray and Ryan,
Ya'll didn't say which version of book you are using, but since there haven't been too many updates maybe this will work for most versions of Moodle 2.x.
Only a few lines of code in ...yourmoodle/mod/book/view.php needs to be duplicated to put the exit book link on each page and keep completion tracking as is. You can almost do it by commenting out one line of code (160) but then there would not be an exit button on the last page and the completion tracking would be messed up. You need to duplicate lines 161 thru 164 and stick them between 159 and 160.
view.php BEFORE:
view.php AFTER:
HTH,
AL