if you know the right people, you can get super short rubber stems. they use them on lawn tractor wheels. i use them on my wheels. id say maybe an inch long total. but, ya gotta know where to get them. i got mine from my shops tire repair supplier guy.
X2 on flush mounted stems, major PITA! dont use the high pressure metal stems either, they are meant for major psi. the high pressure is what holds them in for the most part.