Might be your preference, but I don't use any lube wads in my stack. Just not a need.
If you want to use a lube wad, place it in the stack above the nitro card and below the shot. Don't want that lube getting into your powder.
If'n it was me, I'd put it over the shot below the overshot card.
Or in reality...I'd just use 1 Fiber wad, then shot, then the overshot card, then seal the card in with beeswax.
Nobody says the stack has to be flush with the end of the case mouth.