LJ, use a sharpie pen and write directly on the hoof. Great example in this album:
https://ecir.groups.io/g/CaseHistory/album?id=9848&p=Name,,,50,2,0,0 
I'd probably use "H" for the hinds instead of "R" but it's very clear which hoof is which.

Then after you upload your pictures, you can rename each photo right in Jesse's photo album using the Edit button under each photo and then click Update. Regretfully, like all careful work, it's work.
--
Cass, Sonoma Co., CA 2012
ECIR Group Moderator
Cayuse Case History Folder                Cayuse Photos
Diamond Case History Folder              Diamond Photos