"stressless" and "zero gravity" chairs

I am now 2/3 through the course and have adapted my car seat for stretchsitting and my dining room chair for stacksitting.  But I am having problems with the other three chairs I sit in during the rest of my day.  I have been using what I thought were really comfortable chairs that keep my spine straight and my knees above my hips, but now I notice that all three cause my pelvis to tuck, somewhat.  For tv watching at home and for work (I don't use a computer at work since I am a psychologist), I use leather "stressless" chairs with a footstool.  Outside, for reading, I use a light weight Zero Gravity chair.  Can I adapt these to make them work better?  I have been experimenting with checking my pelvic tilt frequently and trying to find the right place for a small lumber pillow, but I wonder if there is something else to do. Thanks