I finally have a workflow that I'm really comfortable with for my spendable utxos. First I withdraw them to a Samourai wallet on an old Android phone. I let them sit there for various, non-uniform amounts of time. After letting them age, I use paynym to transfer them to a different Samourai wallet that's connected to the Ronin back end. From there I mix them in Whirlpool and keep mixing them until it's time to spend.