Basically, I'd like a line of buffers which will first check at least one (preferably more) adjacent inventory, and insert into it until full. Once the inventory is full, it will then move on to the next buffer, and continue down the line until the end.
I'll probably end up just using Extra Utils transfer nodes...
You can do that with electric sorters.
Set them to output stuff to the BLUE side, and if it cant output stuff to the blue side (aka inventory full) it will output them to the RED side (going to the next sorter), which can repeat the process all over again.