Lots of good advice! What a/c are you flying? It may be a good idea to make sure your mountain instructor has time in type.

I'm not sure 100 hours is magical. If you get the training, understand how it affects your particular a/c, and are comfortable, you should be good to go.

Have fun and be safe.

One thought, and it may be handled in the mountain course, take your plane to 9K (i.e. TEX elevation) and simulate a takeoff to see how your plane performs.