Properly wired and running on a flip flop I don't see how that would be any issue at all. You could probably get away with it even without the flip flop but I would imagine that the ~3000 total watts running at a time would be easier to explain than ~6000+ total watts if you ran them all at once. Either way, pay your bill on time and take care of everything else properly and you have removed just about as much risk as you can...if they want you, they're going to get you, so take care of every variable you can yourself and roll the dice on the rest.