Pete, you might break something but it won't be the mast. It will flex and bend but that's what it's supposed to do. Remember though, as you are sheeting extra hard and with 2 on the wire, you are putting a lot of stress on the fore stay, and the jib halyard, so be sure you look those over when you are rigging it up.

You can break your jib halyard if you don't adjust it for correct luff tension with the main sheeted on hard. The easiest way to break it is to tighten it up real tight while the main is real loose, like at the end of the run, or on your way out to the starting line, spin up, mast is being pulled foreward, you tighten up the jib halyard getting ready for the upwind work...but...after you snuff the spin and sheet in the main, and put two on the wire, you will have moved the mast backwards, and you can really be over-done on the jib halyard, so be careful.

Don't ask me how I know.