Replying to myself (doing a Gandalf? or merely pretentious? or just slightly cracked? 
) …
I use the map view to geotag my images, and would find the ability to
save preset locations in “find location” valuable, in manner akin to
creating presets for darkroom modules.
This is now reality in darktable 2.4.2 and works simply and well. 
Yes, using mobile phone GPS to create a GPX track file can work - I
have had some success using Android ap PhotoTrackr here 1 but it can be hit and miss. More recently, only miss for me.
I have had one good “hit” recently. Moreover, with the GPX track file in the same folder as the images being imported, darktable automatically applied the track for me, without my needing to use the geotagging module in lighttable. Very impressive! 