Resource capacity analyzation for Prospect Projects

I’d like to ask the community what their process is for workload and capacity planning, especially on work that is getting to the end of the sales funnel

We use Wrike to manage detailed tasks and milestones for current active projects.

However, we would like to start using it to schedule upcoming sales prospects as it relates to resource availability with the current workload.   We would like to avoid having to create a full project in Wrike for prospects. 

How do others successfully forecast potential workload in Wrike?

Thanks for your feedback!