Different taxonomy variant based on URL : default for map, other for list

Brief: I want to define a slightly different variant for my taxonomy panel page based on a parameter in the URL.

Detail:
I have replaced my default taxonomy pages with panels. All good. Great tutorial here:
http://drupaleasy.com/blogs/ultimike/2010/10/taxonomy-term-pages-steroid...

Using pathauto, panels 3 and views 6.x-2.16

My use case is to have a panel page that includes a map (amongst other things) of locations of a particular type based on a "location type" taxonomy; open, closed, proposed, etc. All works really well, e.g. www.example.com/category/location-type/open

But, now I also want to have a taxonomy page that doesn't show a map, but instead has a list of locations.

I can't work out how to create that variant, i.e. www.example.com/category/location-type/open/list

I tried adding a "Selection rule" with a "String: url path" -> 404 whether on category/location-type/*/list or taxonomy/term/%term/list or taxonomy/term/*/list

I tried duplicating the whole panel -> 404 whether I use a path of category/location-status/%term/list and taxonomy/term/%term/list and taxonomy/term/*/list

Looking at the supplied taxomony pane, it's almost like I need to change the path to taxonomy/term/%term/!param and use the param as a context, but you can't seem to change the path for this particular panel page, presumably because it's special in some way.

Been searching, but not found anything that helps me. Appreciate your time.