Some suggestions...
Tevin--He's atheletic enough to pull it off and he might make
some pretty exciting catches back there. Face it, he'll never
win in the frontcourt, so this would give him a chance to show
off and bring excitement to Miami. Plus, he'd contend for top
back in absence of 'Storza.
Jabi--Also won't win the frontcourt championship and a position
switch might be what is needed to get out of a funk. Plus, he
doesn't have to serve. In the 3 vs. 2 match last year, he really
impressed playing the midcourt.
Solozabal--If for size alone. I'd hate to see how often he'd chop
at the ball and dump, though.
Ochoa--An odd suggestion, but he does catch pretty well. I'd
be afraid he'd fall in love with the long carom though.
Marku--I've only seem him play a couple of times, but his style
might be more conducive to the backcourt.