if you really try to 'roll in place', put your head right down, i would think it would be very difficult for him to stop, regardless of tightness... i'll have to try it. mike jen's turtle/back vids and saulos turtle vids are useful here i believe.
Saulo does this thing from turtle where he start to roll and he "pops" his hips but doesn't complete the roll...it's almost like a shoulder throw. Hard to describe but it's detailed on, I think, the Advanced Turtle DVD from Revolution 2.
I haven't had much success with it, but that's cause I suck. You might try experimenting with it.
Just reread my last post and realized it makes almost no sense. Awesome.