Alright, quick update here. I've really been struggling with the Harbor Freight vacuum pump. It was venting a lot of oil vapor, so I had to put a hose over it to vent outside so it didn't get all over the place. And forget about filtering VG in any reasonable length of time.
Anyway, I went further down the rabbit hole and got a oil-free vacuum pump from AliExpress: https://www.aliexpress.com/item/1000042 ... 4928voZsKV
Just tried it out this morning, night and day experience! It filtered VG/PGA extract down to 2.5 micron no problem!
I've really fallen behind with all the fiddling, but I think I am starting to get somewhere. It's going to be another few weeks to filter everything but hopefully I can make a final report on the filtration apparatus setup.
Whether or not the filtering down to 2.5 micron makes a difference with flavor and reducing coil killing, that's another matter. I think I'll have to save that test for next year.