I'm not an expert, this is just what I've come to learn through my studies, I haven't done it personally (yet). Everyones recipe seems to be different as far as proportions, I don't have my own for what works. I just learned about using sodium thiosulfate as part of the process myself. Having said that, for every 1 gram of PSE you use .05 of thiosulfate. So if you use 10 grams of PSE, you are only using A HALF GRAM ( .5 ) of thiosulfate - barely anything. Here is a resource
They it say it further removes impurities, unreacted iodine and or a byproduct of the reaction called aziridine. You seem to have the right idea. I believe ether works, but supposedly there is better choices, I hear others swear by coleman fuel or toluene.
Remember to add your NaOH and thiosulfate solution SLOWLY to your reacted filtered product.
NOTE: I don't know if it is better to add the NaOH and thiosulfate straight up or if its better to make an H2O solution. I see different methods to get the same results but wish I had the experience because I would know the difference and be able to share the knowledge. So I apologize on that end. This is all "in theory" for me. If I could get the PSE I needed it would be another story.
Anyway, when you get to Ph 13-14 the meth oil base will push itself out of the solution to the top layer. Again, this is where you add your solvent to catch your product and seperate the top layer. This is where you HCl gas and make your snow globe :} Filter and dry and you're good. After you can pour acetone to wash and further purify. Then you can use dry IPA to recrystalize perfecto - you will lose quantity with the acetone and IPA of course but the higher quality grabs you that much harder ;] Good luck, brother, I wish you success o7