Thanks!
I ordered a bunch of cargo nets from Amazon of various sizes, and I kept these made by Trunknets, Inc — because they were the perfect fit and their quality was noticeably better than the other brands':
Envelope Style Trunk Cargo Net for KIA Soul
Unfortunately, the Trunknets-branded nets don't include the particular plastic mounts that I prefer, and the plastic mounts cost $10 for 4 if you buy them separately. It's actually cheaper to buy a pair of these smaller nets for $17 to get 8 of the mounts:
Frienda 2 Pieces Stretchable Small Cargo Net
And you can repurpose those smaller nets for another project. I mounted the smaller nets to the undersides of various hatches to ease access to smaller things like rags, extra t-shirts, etc. BTW, hatch undersides are one of the few places on a boat that don't get wet in a rainstorm, so a small cargo net is perfect for holding a couple lightweight microfiber towels for drying off. ? I also installed a small cargo net to the sloping "roof" of the footwell below the helm.
Since taking the photos above, I added a small hook between the two upper mounts of each net. With 2 or 4 PFDS in each net, I hook the top of the net (in the middle between the PFDs) to better hold the PFDs in place.
When I go fishing, I never use the under-gunwale rod holders. I use the T-top rocket launchers and the vertical mounts on the sides of the center console.
Also, I have an extendable fish-landing net that can still fit into the top slot of the under-gunwale rod holder even with all of the PFDs in the cargo nets.