That's a helluva smart use of a really tiny space! Given what it'll be interfacing with, that should add a lot of bang to your rig. The Peaks is discontinued, so if that's a priority you'll have to source a used one or find a third-party version in 8 hp...but also, you might consider putting a Doepfer A-140-2 MicroADSR in instead to give you two envelopes, but with individual controls per each. Doepfer's got a few other 8 hp modulation source solutions, as well, like a VCS (the A-171-2), quad decay (schmitt trigger, basically), a quad ADSR (with a few control compromises, but still very viable) and the like.