Furthering the dry aging process post purchase?
I don't have experience with the "UMAi Dry Bag", but I have read about mixed results.  I did just finish a 45-day dry prime rib, however.  It worked out very well.  My set up was a refrigerator, with a small office fan inside.  Air circulation is very important, in my experience.  You don't mention how large a cut you have, but you are not going to want to do this if you are talking about individual steaks.  You really need a primal cut.  The more outside protection you have on your cut, the better.  So, don't trim it.  The already dried exterior will protect the interior, and allow the enzymes to do their work.  If it were me, I would avoid the bag, and try to create a space where you can control the temperature and the airflow.