In field modifications of tanks
 

One of the main things missing from the game, probably by design, is customizing the actual vehicle.

In real life tanks are custom made, armor is added in the field, cope cage type modification is also common. Not just in Ukraine but Israel has always added chicken wire to tanks to defuse RPG. In ww2 bedspring armor was added to t34s, depending on how many springs this could add 50mm or more RHA.

Obviously this comes as a tradeoff to mobility.

Could there be a way to "pay" to "up" the armor on tanks? Obviously not as this would be a massive code change, just an idea for oob designers.

Re: In field modifications of tanks
 

Scenario designers already have this ability when they create their scenarios. I have done this in quite a few of mine.