I have flown over the ranges in NZ and can say that 500ft is not enough. The advice on warm clothing is a MUST, not only for in the plane but also in case you do have to make a forced landing. Take plenty of water, a handheld GPS and mountain footwear.
The wind will be a critical factor, study a mountain weather guide as the lens affect from the wind can easily flip a plane over and also force your plane to descend. Even with full power you may not be able to over come it.
Taking a camera would also be an essential piece of equipment