My wifes SL repayments are through an IBR plan (REPAYE specifically) and we contribute to pre tax accounts as much as we can to reduce AGI. Between us we have access to 401k, 403b, 457, TIRAs, HSA, Dependent Care FSA and her state employee pension plan.
REPAYE calculations are (AGI- 150% Poverty Level)*10% and divide 12 to get monthly payment.
There are a couple of different plans that fall under the IBR envelope. Make sure you look into them and make sure you are on the best one for your situation.