I've done several ghetto-tubeless set-ups with the black / "wrong" tape - unsurprisingly they've all been fine

Converted to tubeless fairly recently:

On my old bike I couldn't get the tyre bead to remain in-place so gave up;

On my newer bike I have absolutely no problem getting a seal with a track pump... though getting the tyre on was practically impossible.... until I learned that it helps if you squeeze both beads into the centre groove all the way around the rim, which buys a few extra millimetres to slide the bead over the rim without breaking anything.