this is the most overthought thread on something simple in a long time
I love it
Just buy a couple of metric bolts the right size from your local lowes/home depot (in the drawers in the fastener section) there is some concern about thread pitch, but likely they'll be right on smaller size bolts. Buy some correct nuts for them.
Thread in the dropouts to correct length for clearance, thread the nuts on as your "stop" (or use loctite purple/blue, just something to keep it from turning in transport/etc)
Or just skip it... tighten down the wheel's nuts properly. Unless you are pulling big starts or using crappy locknuts you'll be fine.