I tried this today and liked the results. I can't EVER do anything upside down coz it causes me to lose all clumps and get stringy. But I did do this method upside down with no ill affects due to the capped affect!
I clipped and then capped and then dried.
Only problems-- had to hold the cap up in the air to prevent flat top squish when I dried right side up to take breaks to rest my back and, and I couldn't see my hair.