Thank you! After reading your post, I found a work-around, because I definitely want a rhumb line. (It’s a long story.)
I used Google Maps to make a two-point Line and added a Pin for each endpoint (3 objects total); exported the map to KML; used a free online converter to convert my KML to GPX, imported to PE. I’ve got a rhumb line track, with identified/named endpoints, and am happy as a clam.
Worked a charm! So if I’m the only user who ever requested a rhumb line Track, please ignore adding such to PE. Not worth it for so few requests!
Thanks for your explanation, it was the hint I needed.