If you're a Canadian merchant, you can add a USD bank account to avoid the 2% currency conversion fee. This bank account can either be with a Canadian bank, or a US bank.
Source: I work at Stripe, but in addition to that, previously started a Canadian company using Stripe, and like you did mostly payments to US customers in USD. I had deposits directly into both a USD bank account held at a Canadian bank as well as a USD bank account held at a US bank, and did not pay the 2% conversion fee. I actually never received CAD directly at all.
More details: https://stripe.com/docs/payouts
But yes, other than certain exceptions such as this one, getting payouts in non-local currencies on Stripe is limited, and we're working on improving that.
(edit: This assumes you have expenses in USD, or a cheap way to convert USD to CAD, to avoid a ~2% fee from your bank on the conversion. Personally I've used Interactive Brokers which charges 0.002% for USD/CAD conversions.)