Try to keep your temperatures at 80 degrees Fahrenheit or lower, you want to keep transpiration down as much as possible. Perlite doesn't retain moisture for very long, as one Melodious Fellow pointed out.

What nutrients are you currently feeding with? And what is your feeding schedule like? You'll want to make sure you're keeping a strict eye on it's nutritional needs, which it obviously won't be receiving through the growing medium. If you're doing all the feedings by hand, have you ever given any thought to setting up a drip system? Seems like it would help to alleviate some of your concerns by ensuring the right nutrients are reaching the roots at the right time. But, then again, I'm not a hydro grower and really shouldn't generalize too much about what method might be easiest. Either way, good luck.