Help: Is there any way to create a 'project cost estimate' via the API?

My client wants me to create a 'project cost estimate' via the API. However, it seems that using the API I can only create an estimate, but not a 'project cost estimate.' 

These appear to be completely different structures that are not comparable at all.

A 'normal' estimate has fields:

'Amount', 'Description', 'Quantity', 'Unit Price', 'Item', 'Service Date', 'Tax Code', 'Class' 

A project cost estimate has fields: 
Service Date, Product/Service, Description, Qty 'Your Rate Hidden, 'Your Total (Hidden)' , Markup% (Hidden), Customer Rate, Customer Total Tax [], Billable []

Is there any way to create a project cost estimate via the API with the actual fields and structure of an actual project cost estimate? Creating a standard estimate and calling it a 'project cost estimate' is not the goal, but I would be happy with any possible solution to this issue even if it's complex. 

As an aside, why are all of the project facing features restricted on the API? Projects cannot be created or edited via the API, Project cost estimates cannot be created via the API, etc... why would this be structured this way when there are hundreds of customers asking for these features dating back almost a decade? Why are projects so poorly supported via the API?

Thanks in advance for any assistance provided.