I understand people are a bit agitated over the knee roll as yet another thing but got to say... few things over the years improved my kneeling position more than this simple little 20 quid cork granulate filled thing I got last week. No problems whatsoever, on the contrary.
Get the filling level just right and it works wonders I promise. Sure there is the option of going without but thats a way inferior option IMO. A knee roll weights a couple of 100 grams, no hassle at all and very easy to get used to.