How do you know she needs a bruxism splint(localized 1-2mm recession)?
You would actually recommend a gingival graft for this situation?
Why not simply try a fluoride varnish with your "sensitive" toothpaste?
I have had tons of success for minor situations like this using varnish. Personally I think a graft is overtreating this case unless there is complete loss of keratinized tissue. I think if you explained to her the graft procedure, expense involved, etc.. she may decide that the area is isn't THAT sensitive.