I think the next thing I should pursue is building an enclosure. I expect that it will get hot inside there and I should be able to provide some airflow for the electronics.
But with regard to measurement, I actually taped a a thermocouple to the glass and measured it while printing, so it was dynamic. Your point about movement most likely causing more temperature drop by convection on the edges is well taken - it's possible that it all becomes less of an issue if enclosed and therefore protected from drafts. Building an enclosure is much easier than etching a PCB so I can try that, measure again and compare.
Many of my prints have been in ambient 35C (it's been a hot summer and no AC in my garage) and they still warp if slablike (covers a large area which extends beyond the center of the bed and more than around 5mm in thickness). So I'm inclined to agree that an enclosure should make a big difference because there must be a huge amount of heat lost through convection. But twiddling the spacing of traces may still be worth pursuing.
But with regard to measurement, I actually taped a a thermocouple to the glass and measured it while printing, so it was dynamic. Your point about movement most likely causing more temperature drop by convection on the edges is well taken - it's possible that it all becomes less of an issue if enclosed and therefore protected from drafts. Building an enclosure is much easier than etching a PCB so I can try that, measure again and compare.
Many of my prints have been in ambient 35C (it's been a hot summer and no AC in my garage) and they still warp if slablike (covers a large area which extends beyond the center of the bed and more than around 5mm in thickness). So I'm inclined to agree that an enclosure should make a big difference because there must be a huge amount of heat lost through convection. But twiddling the spacing of traces may still be worth pursuing.