Kevlar layers, or blankets can be adapted to just about any vehicle, if you have the money. A steel, welded up armor job is very heavy, cuts into door openings, and changes the vehicle dynamics quite a bit. (Figure your 4000lb car will be more like 6000lbs, and you lose 2 to 3 inches around every door opening, while your windows become fixed in place, and the doors gain 300lbs each.)
The kevlar setup hangs blankets in the doors, floor jute or pad is replaced with a floor blanket, and the headliner is augmented with another blanket.
Windows again are fixed in place, and thicker bullet resistant ones installed.
I'd go with the W12 over the S8, as it has more tourqe, and you'd want all you could get with the heavy armor laden vehicle.
As for simple mods that anyone can add to the car, many years ago, a good friend of mine who lives in New Mexico where they have a serious car theft problem did this easy fix.
He was into music, so on his car key ring, he had a quick detach ring, with a large size stero plug on it. The contacts on the plug were soldered to complete the circuit, and he wired his fuel pump relay power into a female stereo plug placed somewhere easy to reach, but not easy to see or find/figure out...
Unless the shorted out stereo plug was in the socket, the fuel pump was never going to work, thus the car would not go anywhere with a common thief. (Sure, you could tow it away, but most thefts in New Mexico, end up in Mexico... and they are not towed there.!
)
Cheap, but he did say if you forgot to plug in, and did it when the power was on, it would arc, and burned up the contacts. (Key is plug in before you crank over the power!)
Just a thought, but I've also seen "factory" switches for items that don't exist on the car used in the same way. Get creative, and keep your car where you want, not off with some thief.