This is beyond my comfort level. I am also not deeply familiar with the recent ruling; that story just caught my attention last year.

What I do interpret is that you are performing derivative versions of songs, and you are still reporting it to your PRO which seems appropriate.

Since these are performances, and not recordings being offered for sale commercially, then maybe you are doing all you need to do.

Parodies fly by their own rules as you pointed out, and so do derivatives. When it is only performance based though, I don't know what more you would need to do.

http://tobybarns.com/