Cable hangers or D rings are the way to go.

Need to find a stud cavity from below?

Either follow the electrical where you can, or use a piece of insulation support wire to drill down from above, go into the crawl and find it, measure from it to determine where to drill up into the wall, drill and use some glow rods to fish it.

After fishing, stuff the hole with insulation, or fill with fire stop caulk (both are code compliant).