This is easy, don't ride it. I quit doing pay for charity rides with a minimum long ago. I never had an issue writing a check for a nice donation but when they start to say you need to make us XXX amount of dollars to ride that I wasn't willing to pay myself I just stopped participating. We had the same issue with our local MS ride. They raised the minimum one year by a very large amount, over $100 and that year the numbers dropped in 1/2. After that it was never organized again. I think that's what they wanted in the end however. Anyways just don't. I hated the notion of begging people for money so if I wanted to ride it I paid.
A club supporting its riders is AWESOME but I suggest you support an appropriate amount per rider instead of a bulk donation of X dollars.