I don't turn the governor off, and I'm not strong enough to get the throttle into the detente on some stiff R22s, but I've not had a problem teaching hover autos.
Please note the words SOME STIFF R22S. They do vary, and I have no problem with most of them.
Start fairly low to teach engine failure in the hover? Of course - are you teaching the student to hover at 10 ft?
And at normal hover height, if you close the throttle, keep the machine straight with pedals and cyclic, you don't need to raise the collective very much - certainly not yank it up enough for the governor to kick in. That's my experience anyway.
For the record, I don't teach EOL's to the ground yet; I'm still an FI(R) and I teach them to the hover. When I get to the point that I do, then will be the time to worry about my weak wrists and SOME stiff R22s. That's if they don't change the rules so that you don't teach 'em to the ground anyway, which looks like becoming the case.
As for teaching range autos and 180 degree turns, as Johe02 says, why would you need the detente; you use the lever.