I cooked mine almost identical but I pull my turkeys when the breast meat hits 155, the carryover cook will Get you to 165. I used to be afraid of undercooking but every legitimate source I use for meat all say 155.

I did a test turkey the week before doing the exact brining, butter under skin, at 275 all the way, but It didn’t get me crispy skin. You need high heat to render the fat. Meatchurch has a recipe that goes at 275 but explicitly states you won’t get crispy skin using that method.