You do not have any rights as part of a corporation that you do not already have as an individual. That is the distinction. The corporation has rights, of which you can enact on behalf of the corporation, that you cannot enact on your own. Limits on campaign contributions is one such right.

Because you carry in your wallet a card that declares you a member of a corporation, you are not granted any rights, personally.

I think you're radically mistaken on how corporate contributions work.

Near as I can find, corporations don't have carte blanche to give unlimited money to an individual campaign. In fact, corporations cannot give any money to an individual candidate's campaign.

Corporations can give money to Political Action Committees, but are limited by amount to the same as real people.

Corporations can give money to SuperPACs, but so can real people.

http://www.fec.gov/info/contriblimitschart1516.pdf

http://www.fec.gov/pages/brochures/citizens.shtml

If I am wrong, I welcome corrections, but I think you're off on what corporations can and cannot do.