I agree with this suggestion
If you have a gpx file, trace1.gpx for example, I think there is a workaround for Windows ...
Create an "Open with" entry in xnviewmp to add an exiftool command (see
viewtopic.php?p=183222#p183222 )
Use this parameter :
-k "-geotag trace.gpx"
You can choose a name (double click in the first column) such as: geotag
Select some photos , right click , Open With , geotag
Exiftool will compare timestamps of the photos and those of the gpx file to add exif:gps coordinates to the photos.
I never tried this , maybe i miss something...
I think that if trace.gpx is in the same folder than photos, it will work ; otherwise enter it's full path in "open with... > geotag" parameters
Other way, : use PicaGeotag freeware to create or adjust coordinates on a map. It also reads gpx files.