I also agree that you need a different strategy. The problem with fiberglass batts is that they let air through them easily. If you do not use something to air seal the building/framing bays, the batts cannot do their job, as the air will just move through them and you will loose your heated air right to the outside. The vent baffles on back will do little to help.
If you are diligent about not puncturing the kraft face and then tape the seems that would go a long way. Instead of foam baffles though, I'd build them yourself out of 1.5" polyisocyanurate rigid foam and seal those very well to each rafter and at the ends, as if it were the only insulation you were using. Then put your fiberglass in whatever room is left. This way each bay is sealed all around and air cannot move through the glass.
If you do some research the building science community has figured out that air leakage costs a lot more in lost heat than less than adequate r-value in a tight house. Air leakage is also what makes the advertised R-value of fiberglass batts very optimistic compared to actual results, whereas foams and dense packed cellulose get much closer.
With regard do your initial question, the kraft paper will be a fine vapor retarder if not full of holes. The building science as come a long way on interior vapor barriers as well, and something like interior plastic sheeting is only recommended in high interior humidity situations (inside pool) or very very cold climates.
