Well... I could only find Pulse Messenger - which only works as a replacement for Message+ (as far as I can tell). I also tried the suggestion from jdhatpha to uninstall the updates for M+ on my phone... but this also did not work because in my instance the base M+ on my phone is already too high a version to allow install to the watch.
What does seem to be working for me is an app called Informer Wear by Komparato. I had to pay for the premium version (5 bucks!) to allow me to add M+ as an app it listens for.
I also tried Messages for Wear by Appfour. This worked for individual messages but it does not recognize group texts. I reported that as an issue to them.