I do GTR in the control room for a few reasons but I also came across the problem of no feedback, vibe, yadda, yadda...here's what I do.
in addition to the main (mic'ed) cabonet, I also run a Mesa/Boogie 'Sattellite' (?) 12" off the cabinet and into the control room.
it is situated at the back of the room and pointed towards the player (not at me!) the player can then choose to turn or face straight at it to achieved feedback. with the control room monitors at a nominal level this is fine with out blowing you away.