I initially used all PLA, including for support, and that caused trouble separating the large bridge because the separation layer is not smooth enough. So I switched to PETG and that worked better.
I hear you about the dryness though. Initially, the AMS was below 10%, but now it’s over 25%, so maybe the PETG sucked up moisture. Will run it thru the dryer.
See also my other question where I have the opposite problem: Support layer sticks to the wrong side