The hack I want to do is to modulate the power to the turntable so that it always ends in the same place it started.
It's annoying when you put in a coffee mug or pyrex measuring cup and the handle is facing the back of the cavity when you open the door.
Usually the motor is a cheap AC synchronous motor, the RPM is fixed. So it's just a matter of deciding to start the power late or cut the power early based on remaining time.
Apparently when I was a little kid, maybe 6 or something, I figured out how to deal with this. I was too short to reach the back of the microwave, so if I put something in the front, and it finished in the back, I'd have to call my mom over to help me. I figured out how long the microwave took to do a full circle, and how long it would take to do a half circle. So when I knew it would finish with a half circle, I'd push the food in as far as possible, I'd nudge it with my fingertips. When it was done, the food would appear in the front and I could grab it.
The microwave I used as a kid in the '80's did this. Dead simple, just a rocker switch riding on the motor shaft, triggered by the split pin that attached the turntable base, which controlled power to the motor in parallel with the microwave controller. When the time was up the table would continue turning until the switch tripped. Stopped in the same place, every time.
On the other hand maybe hacking the rotating plate to oscillate vertically a bit, to avoid the infamous energy spots.