Omer,(sorry I didn't see this sooner - haven't been here nearly as often as I should be)
I went back and forth on it too, but ultimately decided to treat them as Power Armor. In my mind, they are simply a lower-tech equivalent of power armor, so they don't function in the same way as proper armored fighting vehicles or even larger mecha. Even if they do offer more protection than smaller, higher-tech power armor, it's basically offset by presenting a larger target.
Here's the card I made for that model (the name is from my own setting).