I have bullet mirrors mounted on the doors of my Mk2 (fitted by the PO I hasten to add).
The pax mirror is slightly further back, which bugs the heck out of me...
Both interfere with the quarterglass and both were completely useless until I fitted convex glass.
Now only the N/S is completely useless. The drivers side is just barely usable.
I'm planning to take them off the door and, if I can see anything through them not too far forward on the wings, I'll mount them there.
If you're going the door-mount route, I would avoid the bullet type mirrors and have them far enough back to clear the quarterglass.