Possible to set up scheduled send with Sales Insight emails?

I've been coaching them to use the Marketo Gmail plugin and they've been using it, but they're now asking if there's a way to schedule when the email gets sent. It turns out that they've historically used Boomerang to allow them to do this. That way, if they're working in the evening, they can schedule the email to go out early the following morning.

I'm not aware of the Gmail plugin having this ability...but maybe someone out there has developed a solution that allows them to track emails AND schedule the email for a next-day send?

Thanks in advance...