HWPs - do you think it's needed? How would you see the dissassembly feature there?
Disassemble tanks into two parts - turret (weapon) and chassis, produce them separately, and then gather chassis and another turret back together to make a HWP you want. This will make the game mechanics more complex and interesting, especially if make chassis progress less linear - as with current armor. For example, you can progress from light tank to a land cruiser with very thick armor, but unable to fly and low ap, or fly "glass cannon's" tanks with nuclear core (explode on death, more FUN for player), low armor or with dangerous vulnerability to certain types of damage and ability to install very powerful weapon, or heavy scout with large ap pull, light weapon and self-destruct option, or what your imagination tell you. It is hell of a work, but i think it's interesting idea to try.