The halfling
tank seems to be the absolute shortest, but I'll second the vote for a SM KFL+ with the OEM makrolon short
tank. It's pricey for what it is (I paid $25 or so from VapeRev for mine a while back), but it's 10mm shorter than the standard setup, and with the V2 top cap
juice capacity seems pretty darn impressive. They make them in 2 diameters, I went with the 22mm, the 23mm would allow for a little more capacity. I stayed with the 22mm because I wanted the tank sides flush with the deck and top cap.
Just some late added food for thought for those like me that enjoy running their mini in as short a configuration as possible. And a bump for some more feedback.