Hah, good book. Got into those books as a kid after reading the short story.
One of my favourite scenes is from The Stainless Steel Rat Gets Drafted (prequel to this one right?) where the sergeant comes in and makes all the chairs retract, and only Jim is left standing, and when the sergeant tries to intimidate him asking if he is a wise guy Jim says something like "No sir, i just always wanted to be part of the army" and the sergeant gets a tear in his eye.
At least, that's roughly how i remember it. It has been literally decades.