The Future Was 8 Bit has the SD2IEC solution for the Commodore 16, VIC20, C64 and C128D.
I love this solution as I can use it on all the Commodore 8 bit machines I have.
Information:
https://www.thefuturewas8bit.com/sd2iec-info
https://www.thefuturewas8bit.com/c16tailmod