A couple questions:

The sticky flap on the PM box isn't as long as 
the flattened box (because of the 3" short side 
of the box that has the little flaps).  Do you 
just tape down that remaining part?

When you take the cut-off flaps and tape them to 
the other sides of the box, do you mean you tuck 
them back into the flattened box and tape them 
along the long (sans-flap) edges?

I'll definitely try this method, thanks!