Spent all night playing with backfocus and tilt last light, trying to dial it in as best as I could. Although I made considerable improvement, things are far from perfect.
Im left with a strange abberation at the extremities of my image, and given the sensor is not even aps-c size, I feel something definitely needs to be addressed.
Details:
Skywatcher Esprit120
Skywatcher 0.77x reducer
Optolong L filter/ Astrodon 5nm Ha
Asi1600mm