Good idea!
You don't need to have your mind fall asleep, just need to lose body consciousness, which is very fun and enlightening on a mushroom trip. I have experimented with this a lot. What you do is after you peak, or while you are peaking is you lay down and relax. Tune in. Visualize your body as just an outline drawn by a thick dark pencil. Feel it as an outline. Then visualize it being erased. Amazing stuff happens then!!!

I used to have a magic sleeping bag I would use. I would eat a bunch of mushrooms and crawl into my sleeping bag and go on a trip around the universe. I would stick my head out of the sleeping bag a few hours later and suddenly remember where I was and who I was!

In my opinion, you may not have a classical lucid dream, but something just as good and that is how mushrooms are meant to be taken!!!!

Good luck, let me know how it goes.