I am entering this rather late as I have mainly been following Johnnys NZ travels.
In the UK there are currently 3 credit cards that do not impose a foreign transaction loading (typically 2.75%).
We use one or more of these during our visits to NZ. It makes quite a saving. Perhaps there are none available in USA.
I have no experience of car hire but we have hired a small motorhome on 6 separate occasions in NZ, typically for about 6 weeks each time. Being UK citizens we also drive on the left, and NZ roads that we choose, have very light traffic when compared with the UK.
Our choice has been whether to pay an additional daily charge, or an accidental damage excess of several thousand NZD.
We have always taken the latter option. With one company, KEA, the bond was always taken from our credit card and then refunded. We lost out on exchange rate fluctuations on two out of three rentals with them.
Our current renter, Nelson Motorhome Rentals NZ, only keeps your card details. This works out much better. We did suffer windscreen (windshield) damage on our last trip, but were not charged, possibly due to our longer rentals and repeat business.
If over the years we had chosen to not to opt for paying the excess we would be very much out of pocket by now.
You have to look at the extended picture, of profit/loss over all your travels. Also can you afford the amount at risk?