NB and Subs if his BB are moving around without support, they should be an easy target with up leveled navy bombers and subs. Use a sub to track them and stay from the coast
The real goal here is to have an equal playing field. If gold is acceptable in a game just say it if not that is ok also. That way if you have made good decisions in your game by not using gold and are wining you won't be accused of false acquisitions. on the gold games people will use more gold because they know they aren't going to be hammered for its use. You would know what the exceptions are which would make the game more enjoyable for everyone
being able to purchase war bonds with gold is just another way of using gold it doesn't Ballance the game when you can buy them. Just supports the lie that you aren't using gold.
Guess that might be possible but why would you want to wait that long to get any benefit from your upgrade you still have to expend the resources to get there or is it cheaper that way in the long run
Just have a location that tracks the amount of gold, cards and war bonds a player uses, and have it show up at day change. This way you could counter gold use with gold use. this would also prevent false accusations of people claiming you are using gold, cards, or war bonds when you are not
I don't think I would drop any of the units just change tactics to fit the new capabilities of the units. these changes will make commandos and paratroopers more useful for their cost.
I feel the real loophole abuse comes from Negotiating a war just to acquire a supply drop. Being able to negotiate to acquire a Province, ROW or share map Requires a certain amount of trust with with the individual involved.