Improving the saddle pose

Ok here is another eureka moment of ahhhh. I notice that there are actually 2 versions of the saddle pose. You can either do it on your heels or between your heels. I have been doing it between my heels and sometimes my knees complain about it. I find it better to do it while sitting on my heels with the block under the buttocks. I still lean back on a stack of pillows because I can't lean back well enough. I am aiming for a pain free yin yoga stretch. I want my knees and joints to be happy.