Weight is the number one reason why we want aluminum over steel. Add up all of the armor you plan or have on your Jeep and I bet you'll end up with a 5000 lb Jeep. My 04 Rubicon fully armored is 3950 lbs wet. Pretty close to stock weight. I'll bet I have a easier time on obstacles that a fully armor Jeep with steel.
I weighed my jeep last Thursday at a truck stop because I needed an actual weight to help my trailer considerations.
Below is an abbreviated list of my weight adding mods, most likely what you are considering an armored up/modded jeep:
Stock TJ Sport -auto
Full replacement front steel tube fenders
Full steel crusher corners with 3" steel flare
Teraflex belly up
Rokmen heavy *** control arms
Currie HD Steering
Kilby Gas tank skid
Poison Spyder Front Stinger
Gen-Right Rear Stinger
Warn M8000 winch with steel winch line
Poison Spyder Trail Cage with Rear Spreader Bar
Rubicon 44 Front with 30 spline alloy shafts
Rubicon 44 Rear with 30 spline alloy shafts
37x13.5 Pitbull Rockers on 15x8 steel wheels. Each wheel and tire combo weighs ~110lbs and I have 5.
CO2 OBA Setup
Warn Rock Sliders
10" Sub and box
And my gas tank was half full.
Total weight 4220lbs with no driver. And that is with roughly 600lbs of wheels and tires.
Now, all of that said, I would love to get to under 4000lbs and if your armor is what will do it, I will most likely be stripping down a lot of my steel. That and your big brake kit, the 37"s push straight through the Rubi disc brakes on steep descents.