Well that sounds like propylene glycol has a good chance of working for you, I like it in some weathers/ combinations but a disaster in others.
Sorry, technique really: if I clarify I am looking to remove build up, usually from the lengths of my hair so give them a good massage. On a 'normal day' when I wash my hair I am cleaning sebum from my scalp and roots, don't really wash my lengths - certainly never did when I used shampoo (and had silicone build up ha ha!).
Just look at the ingredients list and order for shampoos, I don't think the amount of betaine in, say, a cleansing conditioner would be enough to shift certain silicones or polyquats, ideally have the betaine as the first ingredient after water for your clarifying product. But experiment with what you have at home, if your hair doesn't feel right/ like build up you can always purchase another shampoo or nick a sulphate shampoo from someone else in your household.
Using sulphates occasionally might give you unmanageable hair for a week - or it might give you great build up free hair - but it won't cause permanent damage. I avoid them like the plague but that is because I have sensitive eczematous skin and porous colour treated hair.