Your 55 gallon drum will weigh 440# or there abouts with water. You're not putting that on any quad's back rack and tooling around with it. I put 400+# of oak on the back of mine once - rear suspension was completely bottomed out with me on it. It handles 200# with ease though (4 mineral licks), but steering does get lighter with that much weight aft.
I stopped using this little gizmo when I noticed I had bent the rear rack mounting tab. :oops:
You'll want a little cart or something for your drum, but towing that is nothing for any of the 400cc atvs on the market now. Brakes are where a lot of them fall flat. You can get way more mass moving than you can safely stop. If you have any hills, I'd be leery of trying to pull too much with an atv - doesn't take much to get shoved sideways by an un-braked load and end up going down or over.
My arch is a perfect example. This thing will allow me to pull a 3,000lb log, but I can't even begin to control that going down an incline. This one is about 15" DBH and 22' long and roughly 1500#. I wouldn't want to drive it down a hill, while it pulled it up a small incline without difficulty (you knew it was there). I can just about fling that log with my front end loader.
I might end up selling the arch now that I have the tractor.
We've got a pretty heavy duty appliance dolly. It's rated for 800lb, I'm using that as my basis for finding something to mount it on. I probably won't need to fill it up with all 55 gallons, but I know what you mean about it being hard to handle.