Ok, just got back from the field and got through the tuning all the way, I really like this new method. I did manage to get a small amount of D term in this time, that definitely helped. The pitch oscillation is pretty much completely gone, its barely perceptible now, I tried reducing the P pitch a little after the final values, but it didn't matter, so I think the only thing that would eliminate it is adding a little weight on the tail as Chris mentioned. It flies beautifully now, and I left it in position hold for about 5min with winds at 15mph gusting to 20, and it hardly moves, now its rock steady and extremely stable. I still need to tune the yaw, still running mostly default values, but its flying extremely well.
Here's my final values for reference, TREX 500E DFC, Align stock servos, linkages: