savall

Well, I found a partial solution which is to use a skinning macro every 10 sec when the character is not fighting but it's skipping half of the skinnable mobs... Better than nothing but i'm still waiting for help.
(here is the macro in case this topic personally interests you)
#showtooltip
/targetlastennemy
/use [dead] Skinning
 
EDIT : It turns out that it is way more practical to repeat the macro every 3 secs, it will skin every mob as long as the bot doesn't kill them in pack.