Aloha e from Rome,
No need to take your dentures off with your shoes , just place your tongue as referenced above - just behind the teeth, and then forget about it.
Chunyi does talk about different results when holding the tongue at the middle, back, and middle without touching.
I don't recall Chunyi mentioning greater contact of the tongue being important, but then again I'm not there to listen to him everyday either. Of course it gets pretty cold up there in Canada, and Iam2 may have froze off a couple brain cells -who knows. All you need to do is place the tongue at the beginning and don't bother with it again -it will take care of itself.
Much Love, Shawn