That is an interesting idea... However, I would prefer the coil on top, with the tank below it... The way you have it, you will still get leakage/seapage eventually. If you tighten the top down to seal for the wick, wouldn't the wick get restricted from flow? Basically, build a large CE2 (think giantamizer) size rebuildable atomizer - which the ODY/iatty are - essentially.
I just bought 2 boxes of type B tanks plus 20 silicon plugs to replace the caps when they wear out. It was very inexpensive. I can use the same Type B tank on my A-2TM for a month with no problems (usually) before I start having a leakage issue. Plus with my low Ω coils, they handle flooding very well
What I have noticed though with the A-2... to much liquid in the coil "chamber" and I get seepage at the threads and also down through the screw connections. To help with this, and since I use it on an eGo during the day at work... I took an old batt tube and cone threads, and made a large ego cone that goes all the way up to the threaded section for the tank and stops at the . It keeps any leakage contained. It also protects my A-2 connection from catastrophic damage incase I were to drop it.
PS: I actually like your drawing and idea.