Extruding a face without knowing its sketch

Hi guys,

I have this face I want to extrude up to a plane.

Problem is, a part of it has  curvature I don't know how to sketch (don't have the original sketch for that).

Is there some way to extrude a face without sketching its edges on?

Or maybe a way for solidworks to automatically take the edges of that face and create a sketch on the same face with that data?

Pic attached

Thanks!

SolidworksParts And Features