I have a similar problem, but I’m currently trying a different, almost opposite method to resolve the problem. The problem occurs on the lower layers of my part. The outer edge is also surrounded by a wall of support material working as an enclosing skirt. What I think is happening is that the lower layers are building up heat to a point that the plastic is still somewhat malleable, but cool enough to shrink. Being kept at a higher temp, and at the early part of the print, it has more time to continue to shrink as compared to the upper layers that are in cooler air and closer to the cooling after the print is complete.
I still need good bed adhesion, so I am printing the first couple of layers at 240/110. After 4 layers, I am dropping the nozzle temp to 235. After layer 6, I am dropping the bed temp to 100 and adding 40% fan to get the plastic to cool and hold it’s shape quickly. The print is about a 7 hour print and I am 1 hr in. I’ll post my results.
Also, my printer is in an enclosure and I am leaving the door open.