I don't admit to knowing anything about chemistry OR cooking, lol, so I'm just experimenting as I go along. If you keep your batches small and keep them in the fridge, you really don't have to worry too much about preservatives anyway. But it would me nice to know I could take it along for a weekend trip or not worry if I forget to pop it back in the fridge.

Have you tried xanthan gum as a thickener? I find it a little difficult to work with, but it does the job.
2C/ Coarse/ Normal porosity/ SW Florida/ Salt & Pepper
Cleanse: AIA cowash, TJ Tea Tree Condish
Condish: JC Too Shea (as RO & LI)
Stylers: CJ PP, JC Spiralicious