Yes if you are lifting 3x per week I would do GHR on 1 day, Back Ext. on day 2 and reverse hypers on day 3. Each session should have a posterior chain exercise. RDL’s are one of my favorites as well. If you are lifting 2x per week and want to do the 2 exercises you mentioned do one on each of the days. You can even add another oen with the back extensions since I would classify the back extensions as a low-medium intensity exercise as logn as you are not using crazy weight.
Do you think that this might be a bit much on the posterior chain.
It’s just a taught, especially hitting the spinal errectors that much, I know Charlie would have you with spinal errectors like an oil tankers rope. So perhapse this 3 times a week would do nicely then.
If the intensity is low I think you can do them everyday. I use them as part of my general gymnastics work. I’m not sure if Charlie uses them in a high intensity manner… I assumed from his videos that he doesn’t.