4PCS Car Cargo Net Hooks,Sturdy Trunk Cargo Netting Hook Screws Compatible with GMC/Chevrolet/Jeep/Ford/Honda/Kia/Hyundai,Self-Tapping Automotive Cargos Nets Screw Hook

I love the idea of using a set screw. I'm thinking if I use a shorter set screw to leave some threads in the knurled knob, I could place one of these over top the knob. https://www.amazon.com/dp/B0FHWLBCM8 I picked some up already. The OD of the couterbored hole is 7.8 mm, so just drill out the smaller thru hole, then secure with an M6 BHCS to the knob. There is enough room for the button cap and overall diameter is near match to the OD of the knurled knob. 25 mm set screw and a 20 mm BHCS should do the trick. Did you source your knobs from McMaster, too?