I used a 1/4”- 20 sleeve anchor bolt. I removed the bottom two Philips screws on each bucket and replaced them with the sleeve anchor bolts minus the nuts and sleeve parts. I used 1/4 copper tubing to hide the threads that would be exposed. Everything was painted black. Here are some pictures of what I used and a link to the thread with a picture of everything in place.
I hope this helps you.
Steven