Dear Travis,
As Gabrielle has said there are tools like HLB or the more modern HLD ( an excellent site for explaination of HLD see HLD | Practical Surfactants Science | Prof Steven Abbott ) that can be used to find an emulsification system. She and Michael are on the right track that it will probably take more than one surfactant to do the job. Surfactants are highly synergistic and mixtures often work much more efficiently than single ingredients. I know this is inconvenient when you are trying to minimize cost and supply chain but that's what usually happens.
I would also comment that stability in emulsions is a matter of degree. Every emulsion (excepting microemulsions that are a special case) is thermodynamically unstable and will separate. What we usually agree is commercially "stable" is something that will hold without separation for a period of 6 months - 2 years depending on the industry. They are also notoriously sensitive to temperature - what is stable at room temperature is not necessarily "stable" if it is shipped for a week in a truck where the temperature goes over 100 F or under freezing. This means that you have to test for stability under a number of conditions.
I apologize if this information is already obvious to you.
I was a commercial formulator for a consumer package goods manufacturer for many years. By now you probably have help but I also do commercial consulting if you need more help. karenwiz2016@gmail.com
Good luck with your project.
Karen
