As far as ancillary practices, I'm a big fan of AIS because it helps with getting your body issues out of the way, and works with intent - so it kind of supports the solo work in both ways.

Yoga is awesome. It is not as good for stretching as AIS if you ask me, but it is awesome. I'm a big fan of para yoga for people with healthy bodies into this kind of solo work, and a big fan of forrest yoga for people with body (specifically core) issues. I'm sure others are fine too, I'm just telling you what I have found to be helpful so far.

I'm not a big fan of kettlebells personally. Use bodies as resistance, I say.

Rob