I went to talk to Sibbi in jail and he gave me the strongbox key, THEN I decided to go tell Maven what was going on. She told me to just go take the horse... got attacked by the mercs when I did that, killed them all, emptied the strongbox... but didn't get the horse's papers. I had some glitch where it looked like Maven had given me the papers when I talked to her, but found out after leaving the Lodge and riding the horse for weeks in-game that this wasn't the case. I noticed that the quest was still active in my journal. I had never seen Louis again at that point and had no directive in there about meeting up with him again.
But not having the papers bothered me, and I wanted the quest to update and get out of my journal if possible, so when I went back to Riften to get married I made a side trip to the lodge and got the paperwork. When I did the quest updated and I got the directive to go meet Louis. So I did, and convinced him to let me keep Frost and the quest got marked off as complete.
For the longest time I never saw anything else of Letrush and thought that somehow I had beaten the glitch, then I stopped by Whiterun and... there he was. Just one of him, though. I left him there for a while but eventually I just used the console to disable him. I suppose I can do the same with any clones, but so far I haven't had any.
I really thought that my bassackward method of finishing out the quest had saved me, but I guess not.
