We were talking about similar ideas on our team as well. I feel like that design might distribute the weight too evenly. But maybe that's just because it's a simple idea of your design and not the actual thing. I feel that a lot of people are going to be working with these ideas, which I'm really looking forward to seeing. I also think a configuration like this would make going through the tunnell faster. But again, I also feel like it would be more effective if one end had larger wheels than the other. Like this toy:
But again, I'm not 100% sure.
On another note, I think writing your number like an ambigram would be really cool to see!