So your stumbling block is whether Mary was "full of grace" or not. If you use the term "we" someone might misconstrue who you represent. Who do you represent ?
It's not a stumbling block for me. It's true that Mary was a recipient of great grace. But that fact doesn't have the entourage of inferences that typical Catholic teaching assigns to it, i.e., it doesn't imply sinlessness etc. The problem is that the Hail Mary, esp. as used in its English form, carries nuances that go beyond the teaching of the primitive text. Those "nuances," however weakly inferred, have been codified and presented as the teaching of Rome. That extra baggage is no stumbling block to me. I see it and step around it. But many precious souls are being injured by it. And so I raise my objection.
As for "we," I am simply speaking as a Christian of Protestant heritage. I do not seek to be an official representative of any human institution, but simply wish to be obedient to Scripture:
1Peter 3:15 But sanctify the Lord God in your hearts: and be ready always to give an answer to every man that asketh you a reason of the hope that is in you with meekness and fear:
Have you guys an infinite supply of straw?