I wish I had 80 column mode back then for the c64.
The Chameleon seems to be a good add-on. I would have to see if it has 80 column.
When I looked at the source code in the link, these are routines to use a graphics screen to emulate 80 column mode (or implement an 80-column bit-mapped screen, however you want to look at it.) I know Novaterm did this, and it worked very well, though you needed a monitor or a good TV to view it clearly. Fortunately I had really good eyes.
Does the C128 have the ability to turn off the display like the Plus4 has?
I don't know how the Plus-4 does it. I know I've seen the 80 column screen blanked, but I have no clue if that was hardware blanking or a trick like changing colors to all black. So much old code to go over!