If you bill in USD, and your client pays in USD and you deposit their payment into your USD bank account, then no MultiCurrency gain/loss occurs until you trnasfer funds from your USD to your CAD bank account.

Since there is likely only one or two revenue accounts (service revenue), you may be able to set this up fairly easily with just a separate control account for T&B customers.

Your Adagio Consultant should be able to assist.