We've whipped up a profile-matching 2button SideAux for the Boss 500 Series pedals! Available in 2 models: One with latching switches and LED's, and another with just the plain old Normally Closed momentary switches.
The latching switches are 3PDT so they do have a small click to them, but we are using GØRVA Design Soft-touch 3PDT latching switches! These have the quietest and most reliable latching on the market.
The bottom of the LED version contains a hidden toggle switch, to allow YOU to decide when you want it illuminated: when the switch is latched, or when the switch is open. There's only 1 toggle that changes both LED behaviors.
The latching LED version does require standard pedalboard 9vdc center-negative power.