I would agree with Kallis as it is more equitable. To work nights means a loss of your own time which is why your partner is paid extra and all of that money should not go to creditors.
Anyway Melstel you have to decide what is best for you, your partner and your American properties. Do not worry about the rest of us having a debate over the internet. There could be a disagreement of opinion tomorrow and the next day etc.
You are allowed to retain overtime if it does not increase your net take home by more than 10% i.e if your take is £1,000 you keep the first £100 and if your take home is £3,000 you keep the first £300. After that you split the extra 50/50 with your creditors.