Mount an external disk in write mode from recovery console on MacBook Pro 2012, Catalina

I deleted a partition of my mac and may have to recover my passwords from a file on the disk. I want to make a disk image to allow later recovery and reinstall the system, but I can't mount an external disk in write mode. I tried to mount the disk using the command:

mount -t ntfs -o rw disk13s2 /Volumes/ext/

However, the disk is only mounted read only. [The command csrutil disable](https://www.hawkdive.com/block-or-disable-usb-storage-devices-on/#disable-SIP) is not available. How can I mount my external disk in write mode so I can make a disk image?