The gap between the Vamo and Vivis, Protanks and likely most other 510 devices is an ongoing problem. It's true for the ProVari as well, although there are a couple of vendors who make rings ($$$).
I tried the Protank ring on my V2 again, plus the "B," "C" and "D" type eGo rings, but they weren't right. A couple of other forums suggested going to a hardware store and looking at washers, which might work, but I don't think are aesthetically pleasing due to the flat edge; maybe not. I'm using plain jewelry rings on my mods now, but probably too feminine for you.
But then! Then! I got inspired! I searched
small tapered washers. These probably aren't right (first results rarely are), but it does prove there are possibilities! These wouldn't screw in of course, but neither do mine.
I don't know the diameter of the Vivi connector, but the VAMO V3 (which my guess is you got?) is 22mm in diameter. This washer is 18mm.
http://store.specbolt.com/product_info.php/cPath/85/products_id/120
More parts for cars: