Is it possible to bulletproof an old SUV?

This school year I drive between Houston, College Station, Huntsville, and back several times a week. There is no viable alternate route between Huntsville and Houston without tacking on a chunk of extra time, and I 45 is scariest (to me) in MoCo. Driver aggression is insane.

So….yeah. I figure it's unrealistic, but when I worked in Guatemala a few years ago one of my friends had a bulletproof SUV (can't remember what but it was impressive). Not bec they were bad people; it was a family of heart doctors.

Just thought I'd ask.