Almost all of us have fears of public speaking and the symptoms you mention are classic. I wet my knickers once, I was so scared!
Does your job require that you do alot of this? If so, I would suggest you get into some therapy which will help you tremendously to deal with this phobia. Taking a hit of Klonopin just before you must present/perform will not help you at all. This drug must be taken on a regular, daily basis for it to work and it can take up to three weeks for it to reach a therapeutic level. There are many other fast acting antianxiety meds out there that would work for you in these situations, but I think dealing with the root cause would be better than just masking it with meds. If you still needed a little help from a med while you are learning to deal with this is fine, but make your goal to beat it, which I know you can!
Let us know how you're doing, OK?
Peace
Greenlydia