Hello Kerik,
I'd really like not to use the restrainer. But I just can't seem to get the paper white without it. Can you see improvements I could make in my workflow for developing and clearing that might help?:
Using oxalic soaked Fabriano Artistico per your prep, fresh ferric oxalate, using safelight for the first 30 seconds in the potassium oxalate and 5 minutes total, directly into 4% citric acid for 5 minutes (use this one-shot), quick water rinse, then two 5 minute clearing baths of sulfite/edta.
I hope you are doing well and shooting happily!
-Harlan