If this is what you mean, I've been doing the following:
Play any old Audio sample on loop via Disting (or other sample player, or any Audio input to be honest)
I'm using the Patching Panda Punch VCA which has its own decay envelops on its 2 Channels to create an evolving or changing percussion track which I've been triggering with Euclidean sequences which i can control via CV to that it changes over time.
Punch is a great little VCA with its Accent input too so you can get a groove pattern playing that too, it also has Envelop Outs with an Invert switch so you can send that to a Filter to further tweak your sound.
Punch also works great for Acid Synth lines.
I've also used my ALM PipSlope to make an AD envelope to do the same thing coupled with a regular VCA.
The other module i would recommend for this is the Befaco Percall, I don't own it but you can make anything into Percussion with that and it also has Choke so it will shut off the Open Hat with a Closed Hat etc.
As you say you could use an envelope follower which is listening to some other percussion track to get Triggers, gates and a Decay envelope out of it.
Enjoy your spare HP, don't rush to fill every last space, this is not like filling sticker books. Resist the urge to 'complete' your rack, its never complete so just relax.