OP - If you start the night with a 98-100% charged bank, you should be OK overnight.
Good input to turn off and control the times as much of the fridges features as possible, ice making, set defrost for during the day.
Also even better input that you have many more systems drawing power then the fridge, which is additive to the both the CPAP and existing power draws. And it is the 'total draw down' from the battery bank, that matters - not just the new fridge. (Which also remember, is replacing an existing fridge, probably LP/120 fridge, which was also drawing at 12V while in the LP mode. So, say conservatively it draws 25% of what a residential fridge will draw overnight, which means your new fridge is actually about 75% additive draw down.)
If you are planning extensive boon docking, have a shunt valve and power reading meeter added to your system. Know and monitor and take sometime to understand what this meter is showing. SOC (State of Charge) is the easiest to understand. Trimetric is one of the most popular meters.
Trimetric Battery Monitoring System
As I was adding an all new Magnum MS2812 system, I elected to use the Magnum BMK Meter, which is a good one too.
Many factors to maximizing the life of your battery bank, but one key habit is to stay above the 50% SOC level draw down. Battery life, is all about total cycles - and simple math of battery life, is that the lower your regular discharge, and then recovery back to 100% SOC, the faster you use up the available total life cycles of any battery bank. (We try to keep our night discharge to between the 70-75% SOC level when boon docking, and have added battery bank capacity to do this. Lifelines a expensive, so maximizing battery life is facilitated by oversizing your battery bank a bit.)
Without a meter, you're running blind
! But again, simply put, if you are close to fully 100% at the start of the evening, you should be fine in the AM.
Best of luck to you, and have fun,