Add to SRV additional small electric engines and a small openable solar panel. Then you can use the solar panel (if you open it) on the sunny side of the planet to loading an emergency accumulator (if it get needed). Yes, if you run out of fuel, you can't use thrusters, and these small electric engines maybe aren't so fast, but you will have some kind of safety net against total failure. Especially on some long term missions and expeditions.