There are actually a lot of people on here who do conditioner only styling. To each their own. There are just so many factors like you said that can affect a person once going cg. By all means stick with something when it works! I've never heard of the breaking out because of SM. Are you sure? Maybe diet not in check or something else? Regardless if you don't like cowashing too much you could incorporate low poo into your routine. What is your type/texture like? Many do this and it helps with the so called "build up" that you were saying. I would highly recommend a protein treatment perhaps? I totally understand what you mean by the prescription style regimen most people are given but it is much more complicated. I've never seen anything like this with someone going cg. Idk its definitely new to me but no means impossible. Let me know how it goes! Try lalsg or suave? Their both fairly cheap and easy for most people to get their hands on. That's all I used yesterday and my hair looks awesome today!
*Current Routine*
CO/CW: CJ Daily Fix, GR Restorative, SM RSB, SM SFC
DC: SM, CJ Rehab, G.Nutrafix, DIY
Sealers: an oil, JC N&S
Stylers: just CO, CJ CIAB, KCCC, aloe gel, FSG
Once in a while: ACV, Lemon-Aid

Oils to seal, rinse, and/or pre-poo as needed

2c/3a/3b coarse, normal porosity
CG since 2007