Formulating conditioners: Thickening a leave in conditioner

In this post, Conditioners: Modifying the leave-in conditioner with Incroquat CR, Allison asked: If I wanted to make this a little thicker, say, about the consistency of a light lotion, what would be a good thickener to add? Or perhaps just more BTMS? I have such bad luck with spray bottles getting clogged/malfunctioning that I think I’d like…