Will I damage a cordless drill/screwdriver if I "over-torque" it?
You can but it would be easier and more efficient to bring a manual wrench. A wrench or ratchet will let you apply your torque closer to the same plane as the head of the bolt. Turning the drill will be like a ratchet with an extension on it. Use the right tool for the job, your tools, your watch, and your wallet will thank you for it!