I have this problem quite a lot when we are racing. I think if you want to keep full sails in a F5 then you booth need to hike like mad and flatten the sails as much as poss. I was advised that you need loads of mainsail leach tension – something like a 16:1 kicker!! I think there posts on that one are here..
You might want to get a jib jib rather than an genoa. I think if you can’t keep the boat reasonably flat and your are spilling all the time then you have too much sail up and your are probably going sideways too much. At least with a jib you might be able to sheet the main properly and sail the correct course.
BTW – It’s possible to capsize a W with the main flogging and the genoa cleated – It almost happened to me at Falmouth in 2000 – we got a prize for surving that one 😉