I have a twisted 26ga 5/4 coil at .52 ohms in mine with a 2.5mm 400 SS mesh hybrid wick, I use a small bit of cotton at the bottom of the wick inside of it and almost solid SS mesh at the top. The RSST usually resides on top of my
highly modified Smoktech Natural(not the telescoping one) because it really looks like it was made to be on there. Takes a bit of fiddling to set the wick up the way I have it, but it works so well that I haven't bothered to take the coil off or rebuild it in any way for almost a month. This is the setup I take with me almost everywhere if I plan to go somewhere for an extended period of time. I'm able to keep the fill plug in and it still wicks just great. Haven't really had any leak issues with it yet either with the way I have it set up. I just throw it in my pocket and go.
The coil does get gunked up depending on what juice I'm using but I usually just pull the wick out, dry burn the coil until it's glowing red and very quickly rinse it under a slowly running faucet, gets rid of all that rusty looking stuff and the black gunk. Then I slide my wick back in and it's ready to go. It's not a massive vapor producer, I built it more for flavor and the ability to take long 7-8 second lung hits. I leave the clouds to my RDAs.
Edit: forgot to mention, I drilled the stock air hole out to 2.5mm