I've had my most successful WILDs when I've gone to bed early or early in the morning when I've woken up for a bit then gone back to bed. I've also had some crazy lucid dreams during the day but not WILD and sometimes as a result of caffeine.

What a previous poster said about not worrying about your breathing in the like is on the dot. It might be hard to ignore the vibrations and such but if you continue to focus on your chant instead you might have better luck. Eventually you might roll out. Sometimes I've ended up falling through my bed or felt like I've been yanked out by my feet.

My biggest obstacle is that sometimes before more somewhere around SP I also see and hear weird things. Sometimes I'll hear my name whispered right in my ear which had shocked me right awake. Not focusing on these things as well as your breathe is the key so you can focus on your chant/dream.

Practicing meditation is one way to practice letting your body go into autopilot while you still maintain awareness. Increasing one's focus is key, and different forms of meditation practice (including quiet prayer if you prefer) will help do the trick. Best of luck.