Probably save a lot of trouble just to leave the DVD drive where it is, and get a small external SSD to be "the second drive"...
Thanks for the reply!
this is what I am doing now, I have a USB3 going to a external drive running a WD 500 with Monterey.
just the external drive has a button to power on and the chord thingee is getting a tad uncomfortable.
my concern is doing something were the drive breaks
or something falls off like the Mini, but im not touching the logic board.
recently had to replace the ribbon connection to the internal drive which was no problem.
what is nice is Monterey on an external can retrieve file from the Mojave drive.