Actually, as a military policeman I did observe field grade officers, and lower ranks, "adapting" their uniforms. And surprisingly frequently. It was my job to remind them that it was not allowed. Beyond that all I could do was call it in and have the desk inform their commanding officer ... which was usually a waste of time. Anyway, most of us MPs wore open top Airforce issue holsters for our 1911s rather than the flap covered cavalry model the Army issued (for obvious safety reasons).* And we wore the white lanyard braid through the epaulet but cut off the extension to handgun (again, for obvious safety reasons). Sam Browne belts were still part of the uniform but no one wore them (strap across the chest could be VERY unsafe in a physical altercation). So technically we were also in "violation" of uniform regs. Pretty hard to pick on someone else unless they were extreme. Long hair and/or mustache was the most frequent issue with officers. Warrant officers could pretty much dress as they wanted. Even saw some with beards. But those guys were in but not in the Army.
It would not surprise me at all if Boddington cut off his khaki issue pants while stationed in Iraq. The officer dress khakis in my day were lightweight very comfortable wrinkle free permanent pressed "poplin." Something like this would have been issued to Boddington but almost never worn in a combat zone. I saw MANY GIs playing baseball and golf in cutoff khaki pants. Anyone who had to work in khakis usually bought officers' poplins at the PX and used the issue crap for whatever. We never bothered anyone wearing the pants with civvies. Not the shirt though. Same with OD fatigues. Possibly a uniform violation but who cares? Knee blows out and you can't patch it. THAT is a violation. Why not cut them off and make them civvie shorts? A lot of guys did.
*Airforce SPs were issued 357 revolvers (Smiths I think) and our 1911s fit in their holsters. Don't ask how we acquired them.