Hi
Bitmex:
www.bitmex.comDeribit
www.deribit.comIn both you haven't to verify personal data, so I do not see any inconvenience that you use it in the USA.
I checked out bitmex but their margin trading fee's are .375% which with 5 BTC translates to about 15$ fee each time, that is worse than kraken.
Maker market fee are -0.0250%, you are paid when create an order and are taken for others.
https://www.bitmex.com/app/fees