so i needed to hop in a corny as secondary, but i didn't want the bag to clog the dip tube. I took the air in dip tube (the short one) and drilled a hole at the bottom of it. re-assemble as normal, then take a small piece of stainless steel wire (safety wire for you mechanics) and put it through the hole and the hop bag. now i can pull the bag out in a couple days (or near the end of the keg) and not worry about clogging the keg.
realistically what i'm going to do is dry hop for 5 days and then transfer through my plate filter to the "finished" keg, but it should work the same for any dry hop needs in your "finished" keg.