A Hobie 16 is great in those conditions, get a cheap used one for those rare days, or put a Hobie 16 mainsail on your F18, you can secure it with a line around the mast and tie a knot in the halyard to hold it up. Or try a Hobie Wave, but it doesn't have a trapeze.

As far as not using the jib, I tried that on my Inter 20 solo, It had way too much weather helm. I found it was easier to use the jib and then ease the main sheet and traveler a bunch in the gusts, the jib will keep you moving so you can steer and you won't be fighting the weather helm.

Also, pull the boards up at least half way, that will keep the hull from flying up so much. Sail it low and fast, back in the foot strap, it's a blast!