Well, I didn't know Amanita muscaria was to be used for culinary purposes at all lol 😉 also I asked around and were told by some of those who collect L. nuda, as you've mentioned, that frying is enough.
In addition, I've also been told that if one decided to precook them he should soak them in cold water for a few minutes afterward 🤔
Most of the info I use is taken from the site www.mushrooms.org.il - it's in Hebrew but google translate should help you in that matter, put aside the Hebrew names of the mushrooms which can be translated wrong.
Feel free to contact me with any question in this matter, here on partiko chat or on facebook - nitsan vaisman 😊