I wonder if you really need both an LPG and a MMF in a system like this... gives you options of course, but I'd be tempted to pick one or the other. That said, the closest thing you have to a VCA is the Sinc Bucina... so I'd suggest cutting a filter and adding in a 4hp VCA of some sort, then using the last 2 hp for whatever cool thing you can think of that will fit (including the Meng Qi dual LPG, if you absolutely must have one).
Last thought: Nonlinearcircuits makes a 1u version of Sloth that would be a great fit in your 1u section, if you can stand losing the USB port. Excellent random/chaotic modulation for MG. Of course, you could also add Intellijel's 1u dual VCA in this slot. But Sloths is always worth the hp...