Suggestion for setting Roth Conversion limit to be able to take advantage of American Opportunity Tax Credit

I am attempting to estimate whether it is worthwhile limit my Roth conversion in a particular year to a value that allows me to take advantage of the American Opportunity Tax Credit. This is a $2,500 per child credit if you have a MAGI of < $160,000. The tax brackets limits available in the Roth Optimizer are such that it would put me too far below the $160,000 limit to be a reasonable estimate of what I am trying to model. Also, what would be the best way to input the tax credit.

Thanks.