You can use the ice armor epic to get a decent amount of smashing and lethal defense. You can then get 25% or so defense to melee on top of that (12ish % of that is defense to all which should get your smash lethal up into the high 30s).
That should be nicely survivable at the speed that you will obliterate mobs.
-Insanity is doing the same thing over and over again and expecting different results. - Albert Einstein.
-I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended us to forgo their use. - Galileo Galilei
-When injustice becomes law, resistance becomes duty. - Thomas Jefferson
Hero Plan by Mids' Hero Designer 1.401
http://www.cohplanner.com/
[u]Click this DataLink to open the build![u]
Yeah, I don't think I'd drop my ranged defense quite that low. The alpha tends to be ranged attacks and the mobs switch to melee for the second attack especially if you hop in with hot feet running.
-Insanity is doing the same thing over and over again and expecting different results. - Albert Einstein.
-I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended us to forgo their use. - Galileo Galilei
-When injustice becomes law, resistance becomes duty. - Thomas Jefferson
I wouldn't run that fire/fire build personally, it was just in response to the question.
That said, put a stealth in sprint to reduce ranged agro on the alpha and then pick and choose the enemies you face and you'd be a monster.
I'd imagine a fire/fire pbaoe focused toon would generally have to be careful who they are fighting in the event that a good tank/troller/dom is not present. 
What would you think of a build with in the range of 32.5% melee and ranged defense?
You'd be softcapped with 1 small purple, still have significant mitgation without it, and hopefully the build sacrifices would be less severe - since ranged defense is easy to get.
id like to see it
Done!
WT
So...I was racking my brains tryin to come up with a Fire/Fire/Whatever build for jumping in and aoe'in large groups to deadness without becoming a part of said deadness
My question is...
Is it possible to cap Melee defense on a fire/fire...do I want to or should I stick with ranged defense?
Im doin this to help a friend out...so not much experience with fire/fire...gonna keep working but any help would be mucho appreciatedo...