What size sail were you on? I've never been out on a foil above 30 because those winds are quite rare here.
I've been in a few survival situations where it was gusting up to 30 and I was still on a 9.0, and it was extremely tiring and uncomfortable be do anything other than just commit to the foil. If I got out of the straps, even the front, there was enough speed to get up on the foil, especially sheeted out, when going downwind, and I felt like I had no control over the foil, but don't take that as 100% as I'm still quite fresh.
You may be able to stay on the foil and just hold the mast, essentially, or just "idle" the sail dead downwind, with wind that strong. It'll be more comfortable than dealing with the waves and the floatation fighting you as long as you control your height. Usually I just go as deep as I can downwind, which is sometimes quite deep, and still stay up on the foil and have my hands on the boom. If you had a small rig you may just be able to do that and use the 20mph or so of apparent wind to get rid of the big gusts. Just steer deeper in the gusts. It is definitely a bit scary though.Also, check out this video, it's been out a few days and it immediately gave me better control with their hip movement.