It's a really tough point of sail on any of the F18s that are so refined specifically for upwind and downwind sailing. Here are some random (mostly unorganized) thoughts:

If it's windy enough that you are wondering how to depower, I over-ease the jib and focus on the main. We have a doubled up sheet take-up system in the main beam that gives us enough jib sheet to ease it in this case. If you can't ease the jib enough, you are choking off the bottom of the main and driving with the upper part of the rig - which also doesn't help your stability. If your crew can run the main, it really comes in handy here. Ease the traveler so you can sheet the main as hard as possible but if the traveler is all the way out, that's pretty much it. As you noted, the apparent wind can swing wildly as you accelerate and decelerate and if you have a lot of twist in the sail the top part of the rig will start to power up if you stuff it and slow down - making the tipping forces worse. Flatter is better. Downhaul on as much as needed. One of the biggest helps is to get the boards up in almost a downwind position - they'll help keep the boat from tripping so quickly. Talk before hand with your crew about what the emergency exit manuever is (steering up or down, easing the main, etc.) and we sometimes agree on a short word to announce the emergency depower move (usually an expletive).

You do all this and you will still be on the ragged edge. Waves make it tougher...staying at the back of the boat is really important but if you are double trapped, it requires a full commitment to survive there...there is no half way to go fast on this angle. However, you should be able to trust in one thing - you are moving so fast and the crash will be so sudden that you will probably be thrown safely clear.


...and consider a drag sock to clip to the forestay bridle and throw in the water if you flip to keep the boat from accelerating away leaving you body surfing after a capsize.