I'll break my outside players rule for Bruce to record this song. Bruce is cool and he and Eric were good friends. It would be awesome to have all six guys on one song. And it would just be one song, so any fans who aren't into it wouldn't have much to complain about. Record A Cover Song.
Cover songs are fun.
KISS needs to show us that they can still have fun. It could be any song, really. Something by Led Zeppelin, maybe the Beatles or Jimi Hendrix. They had it ready to go for Alive II, it would be cool to do it now. As for who sings it, I would have to go with Peter.