Rock and a hard place a bit Ed!
If you back off the mic a bit you will reduce the proximity effect that is not helping with the deep voice. Trouble is you then get more "room" in the signal. Broadcasters who use the excellent mics suggested CAN be back a bit because $10,000 has been spent correcting the room!
Then again, what sort of interface do you have? The SM7b in particular is a very insensitive mic and speech and intimate stuff could well be marred by pre amp noise.
One suggestion if the AI pres are not stellar is an LDC for the sensitivity but one with a built in LF cut (High Pass Filter). Then get at least 6 inches (150mm) from it but get as much room treatment around you as you can. I would gladly loan you my Sontronics STC-2 to try but the shipping would bust me!
Dave.