Did some checking, and the VRL cab's 5V line has 1A available. My concern was that the Nebulae v2 would draw too much for that, but Qu-bit's own data shows it as having a draw of 47 mA on +12, 7 mA on -12, and 271 mA on the 5V bus. If you can get your +12V bus draw down to 700 mA-ish, you should be in the right current ballpark. But again, check the manufacturer websites for the data here, since everything's getting close to those P/S limits.
The other thing I'd consider changing would be the mixer. A better choice would actually be the Happy Nerding 3x Stereo Mixer, I think...while it draws more than the JPSynth one and has one less stereo input, it's also 2 hp smaller and because it has an onboard TRS out that can be used for headphones, it eliminates the need for the HPO, and that opens up another 2 hp. The Nebulae should then fit into the space occupied by the Catalyst (move that to the other row), and this puts your free 4 hp in the other row for use by another module.