'Loft' or similar command to create closed polysurface from the objects pictured

I’m basically trying to find a shortcut which would allow me to quickly make a polysurface between these two objects. This is a simplified example of course, hence why I don’t simply close the surfaces through the various options available, or offsetSrf and then clean up the underside after.

image

I can think of a couple of quick options -

  1. DupBorder both and then Loft
  2. Gumball extrude the lower surface past the upper one then BooleanSplit or maybe CreateSolid…
  3. Sub select the edges of the lower surface and Gumball extrude up past the upper one, then CreateSolid

Thank-you x3!!