Well, best thing to do is try, Try with something cheap, and worse case, you give you puffer a nice meal, if you try something more expensive and the dogface goes for it, itll be a bigger loss for the same experiment. I have a lawnmower blenny with a Stars+Stripes and Porc puffer, and it has been working fine for the last few months.
You said that puffers destroy crabs, but have you tried adding a few hermits and snails to the tank? I have an army of hermits and snails (30+ of each) and they havent been touched by either of my puffers, and some of hte shells are small enough to fit in my puffers mouths.