I have some of those low rider bosses and decided not to use them. That's a really big hole to put in a fork, and it's unnecessary. I got these https://www.paragonmachineworks.com/...fork-boss.html I wasn't particularly happy about the size of the hole I had to drill. The next fork I build with low rider bosses is getting 5mm.

Thousands of Long haul truckers are circling the globe using a 5mm boss without issue, so I'm pretty sure that's a suitable approach. OTOH, the attachment at the dropout is pretty important. I beefed up the eyelet on my dropout, it looked like a failure waiting to happen.