I recommend working with Represent Us to sponsor campaign finance reforms. Their proposals are here, https://represent.us/anticorruption-act/ .
Here is what they say regarding financing campaigns:
“The Act offers every voter a small credit they can use to make a political donation with no out-of-pocket expense. Candidates and political groups are only eligible to receive these credits if they agree to fundraise solely from small donors. The Act also empowers political action committees that only take donations from small donors, giving everyday people a stronger voice in our elections.”
Thanks for the thoughtful idea. It neatly navigates the Constitutional problems with expenditure limits. But it still allows an advantage for wealthy individuals.
This could only work if limits/bans are placed on large donors also. For example, anyone making over 300k a year can only make a 50k maximum donation. Corporations cannot donate any etc.