I worked as a corporate & startup marketer for 12 years before starting my own marketing education and services company.

Launching an outlandish challenge would be great for PR and exposure. In your example, NRA vs Students for Gun Control becomes a human interest story because the results serve as a litmus test of which side of the fence people are more likely to financially support.

The only hurdle would be finding a source of momentum to keep the challenge going. GoFundMe works well because there is an individual invested in the campaign being successful. In the way you've descried your challenge it seems it would be run by your platform without participation from either side to support it. I would look into getting the opposing sides involved to spread the word. A company that does a good job of leveraging momentum in the charitable giving space is Omaze.

Happy to have a call if you have any additional questions!