Remove Conveyor Sorters. Put sorting into inventory blocks directly.
Do away with the middleman. Prevent unwanted items in the terminal of each inventory block directly.
A blacklist/whitelist section for the inventory of (not the pass through conveyance) any block that has a hold and would make sense to have it.
(ie: Cargo boxes, refineries, Connectors/Ejectors, Cockpits/Seats, not turrets or tanks).
Filtered blocks would allow items past, but not into its inventory.