While shoehorns with short handles make me bend over too much, those with long handles slip off my heel prematurely.  The intermediate length of a big serving spoon’s handle works well.  The bowl of the spoon cradles my heel and stays there until I want it to move.  Shoehorns are too flat for cradling.

Tho slow at learning physical skills, I got the hang of using the spoon as a shoehorn quickly.  The trick is to tilt the handle forward while lifting the spoon out from between heel and shoe.  (Pulling straight up would scrap the edge of the bowl along the Achilles tendon.)  The lower leg is in the way, so a slight tilt to the side is needed along with the forward tilt.  This is simpler than it sounds.  If I can do it easily, so can most people w/o specific disabilities.

Does the spoon really need to be brushed stainless steel like mine?  No, but it does need a thin bowl that is smooth on the outside as well as the inside.  Go for metal to be sure.  The spoon will last forever and be seen often, so it’s worthwhile to get one that’s eye-friendly.