I'd recommend getting a hydrometer calibration kit off of Amazon and a sensor that can be calibrated.

here and here

These allow you to get an accurate reading of the temp and humidity. The fridge needed to be set at 49 degrees F to be stable at an actual 55-57deg. Similarly, the hydrometer control needed to be calibrated and adjusted to hold at 75-78 RH. Without these devices I wouldn't have been able to do that.

Yup. That’s exactly the combination I use. We Have 7 of them set up that way and it works perfectly. Only thing I might add is a hygrometer. This is the one I use.

https://www.amazon.com/Govee-Thermometer-Hygrometer-Bluetooth-Temperature/dp/B07R586J37/ref=mp_s_a_1_4?crid=IRLXMZJVSBK7&keywords=govee+hygrometer&qid=1644981509&sprefix=govee+hygr%2Caps%2C52&sr=8-4

Calibrated using this.

https://www.amazon.com/Boveda-One-Step-Hygrometer-Calibration-Kit/dp/B000A3UBLA/ref=mp_s_a_1_3?crid=2PG4OJMQ8X435&keywords=boveda+calibration+kit&qid=1644981552&sprefix=boveda+cali%2Caps%2C57&sr=8-3

Kit says to calibrate for 36 hours but I do it for 5 days. Also make sure to keep the bag in the tupperdor while you calibrate and the tupperdor where you will keep it long term.