Crispy Chicken legs with Water pan?

Could not find leg pic, but these wings were cooked the same way.

@Mickey is correct.  Raised direct is a good way to crisp the skin as it gets radiant heat but the meat is not close enough to the flames to get burned by them.

However, to answer your question - yes I have cooked with a water pan in the egg and it works fine.  Unlike my Weber or my ProQ smoker, the egg can get well above boiling temp as it is better insulated and can achieve a bigger fire and air flow.  It is unclear from your question if you have a platesetter.  If so, what you really want is to put a drip pan (with or without water) on top of the platesetter with something to allow airflow between the platesetter and the pan.  People use a variety of things like balls of aluminum foil, small pieces of hardware, etc and place them on the platesetter and under the drip pan.  This keeps the heat from the fire from being semidirectly transmitted from the ceramic to your pan and as a result the drippings don't burn and give off an acrid smell. 

You may be able to accomplish what you want by simply using a drip pan with water and no platesetter (as I read your post I think that is what you are suggesting/asking).  To get the skin crispy while cooking indirect it seems to be best to cook at a temp above 350.  I let the egg settle anywhere between 350 and 425 and just go with it.

Crisp skin is dried skin.  You can jump start it by drying overnight, but in your case you prefer not to, which is understandable.  We don't all plan cooks a day in advance.

So how to dry the skin then?  Well, by NOT using a water pan, for one thing.

You aren't going to boil the water at 400 degrees, because it isn't the air temp that boils it, it's the radiant heat from below.  But still, water in an environment where you are trying to dry something out is just about the best way to guarantee chewy skin.

If it is drippings directly into the fire which you are concerned about, then just use some foil on the grid, then elevate the chicken on a raised grid above it, with bricks or a raised grid rig (hex nuts, three or four inch bolts, and washers attached as feet to a spare grid).  The drippings will collect on the foil.  They shouldn't actually 'burn'.  When we see puffy clumps of charcoal in our drip pans, it is not because the stuff caught on fire and made black smoke, it's merely (usually) the sugar in sauces being carbonized by the relative high heat and lack of oxygen.  It's literally making charcoal by driving off everything but the carbon.  You don't get putrid smoke from it. It's not the same as dripping into the fire and burning.

Anyway... crispy skin.  Honestly, abou the only thing the egg does TOO well is retain moisture.  If you want dry skin, you'll need to air dry overnight.  Lacking that, you have a couple options. 

Raised high, indirect, in the dome at lower temperatures for a long period of time.  say 250, for a few hours.  This is what works for me.  The long draft gives you a chance to evaporate some moisture off the egg, and the radiant heat of the dome cooks the meat.

Or raised high, direct, over a moderate fire.  Say 400.  This gives you some direct radiant heat from below on the skin.  The cook is relatively short though, and you can get skin which is bite through, but not truly crispy. Any sugars in the rub or sauce can burn, giving you some crispy bits.

I have not done the third option in a long time: high in the dome, indirect, at higher heat.  I seem to remember that this also gave merely "ok" skin, not truly crispy.

Peking duck is dried in advance overnight, and is the perfect example of crispy skin.  Good results require planning ahead, unfortunately.

Other cookers (metal, usually) do well to dry chicken skin, because there is so much draft required to keep the fire going (and much more fuel used).  This continuous large amount of hot air (note: I realize I am leaving myself open to a jab there with "continuous large amount of hot air" :-S ) helps dry the skin quite a bit, as does a hot dry electric oven.

In the end, I have found best results by going slower for a longer period of time.  A whole chicken dried overnight, and cooked at 250 for a few hours, has really crisp wonderful skin.

If you can't dry overnight, try a lower temp for a longertime.  And ditch the water pan.

I haven't tried this yet and it's for a whole, spatchcocked bird, but perhaps it will help. Judy and Joan know what they're talking about.

I dry off my chicken good before applying dry rubs. For legs, I hang them in a leg rack and cook them indirect at 350 to 400. It takes about 1.25 hours until the skin gets crisp. I get crispy skin every time.