I wouldn't use a dual coil on the LT. It reads it as a 1.5ohm carto and cranks the voltage way down below what a DC carto really needs. Stick to single coil 2.5 to 4 ohms. You can get the full range of voltage on a 3 or 3.5ohm carto.
As for tanks, I'm partial to the Vision Stone 3 from Gotvapes. It doesn't use a carto. It uses a CE2 type cup/coil. The innards are replaceable for about $3 and to fill it you just unscrew the cap and pour the juice in. No muss, no fuss. The one I'm using now as my main vape has lasted over a month so far with no sign of burning out. To change flavors, you just rinse it out with hot water and let it dry (or not). Fill it back up and vape on. It holds about 3.5-4 ml and there's no filler to burn or to dry out or to add any funky flavors. Plus, it looks cool as hell and fits the LT like a glove. The one I have meters out to 2.4ohms, which is slightly on the low side, but it's a vapor machine at about 4-4.5V or so. There's no need for me to take it up to 5 or 6V. Highly recommended. I've tried a lot of tanks and they're mostly just a big pain in the ...., especially for thicker juices. I'm done with slotting and enlarging holes and all that nonsense.