Personally, I don’t like the idea of a limited unit that you have to keep extra track of.

What about this:
The last generation of german tanks were prone to mechnaical failures but when not required to risk themselves by moving, they performed quite well in defense.

All tanks German tanks in grey territories or an immediate adjectant country defend on 4 on the first turn only.

Kinda the tank version of Festung Europa, I know.

I wouldn’t buy a third IC for Britain. Particulary not the combo India / Australia. Sure it keeps Japan good at bay, but to take advantage of the two ICs, you will completely neglect Germany as Britain.

My friend had an IC palced in India only, and while he managed to keep India still, Germany is only now starting to feel pressure form Britain, and we have palyed along, long time.