I’m playing a set of pipes with tear drop regulator keys. My hand is averaged sized. I have angled my stock, my bag and my regulators every imaginable way. Im going crazy because Im always sounding the tenor keys when I just want to sound the baritone keys. Comments/suggestions?
Perhaps twist the tenor towards you and the bass away from you, with the baritone pointing straight up? That would leave a slightly larger path for your wrist to only hit baritone notes.
djm
What is wrang with playing the Small and Middle regulator keys at the same time 
That is what they are there for and they make a nice harmonic if they are in tune.
All the notes with the exception of C can be played with a pleasing two note harmony frae the regs.The C is best harmonised with three note GDG the 2 note harmony being GG which is a bit clumsy.
If ye want one note harmony ,and why not indeed ,then either take out the other two regs (Big and Little)and play with the Middle.This would be more in line with the early sets.Or ye could just play the Big Reg.If ye just want to play the Middle Reg but keep the look of the full set(posers I call them 
)take the reed oota the Big and Little Regs and block the end with whatever ye normally use..finally as Gay said to his very first master class on regulator playing at Willie Week( after I had badgered NPU for aboot 5 years to do so) a sentence so touching and actually very informative in its simplicity and which deserves to be in the Pantheon of Piping Quotes.."Just play the feckin things.."Nuff said. 
Slán Go Foill
Uilliam
Its possible to play just the middle reg, without changing the two othter regs. But it needs a lot of practice. If you play the tenor and barinton together , and have controled them , it’s less difficult to play just the middle reg. But play the middle reg with the little bone of palm of your hand. (also when you play the two regs together).
Good luck !