modify fridge to temporarily defeat auto-defrost?
Auto-defrost just raises the temperature enough that the accumulated undesired ice build up (very thin at this point) melts away while still cold enough and short term enough to not melt the items frozen in the freezer. It does this with a heater inside the fridge to periodically warm the appliance during the defrost cycle. Here's a video that explains it.

If you want to disable, you can find and remove or cut the wire to the heater. There should be a wiring diagram on the back and probably down low. Due to your background, I think that you can take it from here