How much weight will both the large and the small melon cradels hold?
Both the small and large should hold over 50 lbs.
What is the easiest way to attach these to a hardware cloth fence? Should I use a D-clips, or is there a cool way to tie them that I haven't figured out?
Hooks or zip ties will support heavy melons. Those are the main options, but as you alluded to, there's a lot of options also probably laying around the house!