I may be the odd man out here, but I think the RN and Canada are being sold short here. A hostile US will cause a different Canadian military, with a larger Army AND Navy. The RN has bases from Canada, Bermuda (easy steaming distance to the US East Coast) and throughout the Caribbean. The RN has a well balanced force, with good radio comms. This also says nothing of what the CSN will have, which will be nothing to sneeze at. All that means you have to either choose a more balanced but smaller USN, or keep the same as OTL, which is badly unbalanced. If the RN decides to move for a fleet action against the USN, they can (provided the USN force is as OTL) almost certainly give the USN a good thrashing.