Here's a good looking demo, with source code, of cone tracing. He's doing it through a 3d texture rather than an SVO, but the principles are there: http://www.geeks3d.com/20121214/voxel-cone-tracing-global-illumination-in-opengl-4-3/
And I don't believe EPIC is really planning on doing ONLY direct light and a single bounce. A very low level ambient term and HDAO is added in (at least some parts of) the Elemental demo as well. Should help with any "I can't see anything!" problems
The other thing you could try, as I assume you're already doing an ambient term, is something Pixar does. They inject an ambient term like amount of light into all points, replacing a normal ambient term with one that gives color bleed from all objects (and specular too!). But with the mipmapping errors you're getting it might look really weird.