I don't think you understand the issue. Your LSI card has 8 ports (port 0 to port 7), if put plug port 0 into slot 1, port 1 into slot 2, ... port 7 into slot 8. Put 1 drive in slot 1 and one in slot 8. Look in DSM and they will show as slot 1 and slot 2. It will fill the slots in DSM in order any drive is detected, regardless of their port #, or what physical slot they are actually plugged in.
Everything I've read said this is the only way the LSI cards work. Also, everything I've tried supported this as well.
I perfectly understood what was said, hence my explanation of the order I added my drives. Putting them in one after the other keeps them in order. I have an 8bay UNAS populated with 5 drives with no issues after adding one after the other from left to right.