Haha. When I was reading this I suddenly recalled a time when I was a kid -- one of the neighborhood boys decided to crawl through the new concrete drainage pipes that were being laid in our neighborhood. He somehow managed to get his foot and tennis shoe wedge in there and couldn't go forward or back out. I think the parents had to call the city to have them cut the concrete apart after trying to manipulate his foot didn't work. Remember him crying in there afraid he wouldn't get out and scared the concrete saw would cut him. Hopefully if you get this off the ground your photo op will go smoothly.
I like the idea of maybe using garbage cans. Some tend to be angled but I'm thinking I've seen straight sided ones. The only other thing that comes to mind, also from when I was a kid, were those really strong cylinder shipping containers. They came with lids that you could seal to ship once you loaded them up. My aunt had books and clothing shipped in several and sent to our house when she was moving across country. Have no idea if that kind of thing is still being sold. Guess there are steel drums but probably would take a torch to cut through them and who knows what kind of substance was stored in them or if you'd get a smooth edge where the bottom got cut off.
Here's a link to the shipping cylinder container I was thinking of. Trick would be finding one used and cheap. Maybe through CraigsList? This place below sells 55 gallon drums new for like $58 but you'd have to buy 2. If you think something like this would work at least you know to look for Fiber Drums in your search. They also sell plastic drums (and other metals) but those are even more expensive per unit than the fiber ones.
http://www.uline.com/Product/Detail/S-7900/Drums/Fiber-Drum-55-Gallon
OK apparently there are companies that sell used fiber drums, here's one. I just googled "used fiber drums" and saw a few listings and some tailored to my state or certain cities. Too bad they don't have any for sale. That $17 price for a 55 gallon looked very attractive. Maybe they have a waitlist. I would check the diameter of these and see whether anyone can comfortably crawl into one before pursuing.
http://www.lexingtoncontainercompany.com/Fiber-Drums-Fiber-Drum.html