We currently do not have SQL overrides in the new version of Method. Since there is no 1:1 relationship with there could be many Estimates related to an opportunity. Once this realtionship is created with the help of customization you can use the custom filters to achieve the above request.
It is a little complex customization but definitely achievable. If you wish to know more about this or need guidance, our consulting team (billable service) can definitely help you with this.