I've read crap load on the subject. While I respect your decision to keep the dark part, trimming is generally regarded as the accepted way. As mentioned above, that's why usually it's primals that are untrimmed nearly exclusive used for this purpose. They have less surface area allowing the enzymes to work on the meat while minimizing the amount of edible meat that needs to be trimmed. You'd never ever see an untrimmed dry aged steak served at a top tier restaurant. Also, to reiterate what some of the folks above have been saying, that is the reason that aged prime meat is so expensive. Shrinkage plus trimming accounts for a large amount of loss of weight. Prices are attributed to starting price/pound to end price/pound plus time and effort calculated from the total price paid. Monitoring humidity is generally used both as safety means to ensure minimal spoilage and as well as to minimize shrinkage while achieving maximal flavor to cost. I've read many many opinions on proper humidity but somewhere between 70-85% seem to be most often quoted.
Just some fun links for those interested:
http://www.beefresearch.org/CMDocs/BeefResearch/Dry Aging of Beef.pdf
YouTube - Good Eats S5E4P1: Celebrity Roast
Hoss: Please don't take my reply as any sort of criticism of your way about this. If it works for you and you feel comfortable with it by all means. I'm just writing those as others might be interested in doing the same and "knowledge is power". Thanks for this thread!
