Hi Jenifer,
To answer your question - you would have control over the outcome in mediation, because you will not agree to terms that don't meet your needs.
I am sensing also a question about how you would like lawyers and "the law" to impact the result of your mediation settlement. In mediation, we would discuss the statute which determines spousal support, and also the temporary spousal support formula, and arguments that lawyers would likely make for each of you. We would also analyze both of your budgets/expenses - with the goal of trying to structure a settlement that will work for both of you. So - even though the law may not provide clear black/white guidance - the facts of your lives will.
Finally - you can always have a consultation with an attorney - and if you are feeling the way that you feel - then you should. You can meet with a consulting attorney, before, during and/or after the mediation. Then you have done your information-gathering, and you can come into mediation with some realistic expectations about how the law would apply to your family - so that you are ready to negotiate for something that is workable for everyone.
Hope that answers your question! If not - please feel free to give me a call.
Rachel