I just did the Paramedic for the first time (before having read this guide), and I didn't find them particularly difficult.
It only took me two "serious" tries (I did 2-3 before that, while getting used to controlling the ambulance, but failed to get past even level 3).
First try after getting the hang of the ambulance I got to level 9, but ran out of time due to the ambulance rolling over a few times too many (not getting destroyed, just rolling around and back upright) and losing time.
Second time, I finished it without much trouble, except suppressing the boredom of repetitiveness.
For info, I did it in Portland (can't get to Staunton yet), having done all missions for Luigi, Joey and Marty Chonks, and a few for El Burro.
Neither Triads nor Mafia were hostile yet.
My main "trick" was to just take it easy, and avoid rolling around or bumping into things, rather than going fast.
Time isn't really much of an issue most of the time, as long as rolling or bumping can be avoided.