We Make Moving Media
So, I wouldn't push it with this line of products because of the flex tilt head, but I will say that I own their small SliderPlus and even though it's rated for 17lbs, I put my full size Ursa on there and didn't have any problems. Plus the staff and support at Edelkrone is great.
I'd be interested to learn more about what you've done, do you have links to photos of your setup or a link to the results from this setup? I'd love to see your system in action and the finished footage.
Just a quick nerdy note - the character of Batman is a year older than the character of the Joker. Batman was introduced in 1939 in Detective Comics #27, the Joker in 1940 in Batman #1. So he didn't make his debut in the first Batman comic, but rather the first Batman solo comic.