Great work.

First, a minor thing: rather than "That which you own you have a right to sell on any mutually-agreeable terms", how about "That which you own you have a right to dispose of however you wish, as long as doing so does not violate anyone else's rights". It's about more than just selling. This would include estate issues, for example, and therefore a rejection of estate taxes. And "disposal" might mean destruction, so there may not be another party with whom you need to agree.

At a higher level, I would like to suggest explicitly calling out support for individual rights. The issue is that trying to name all rights one-by-one is problematic, and it's the principle that's important. You might include a definition, perhaps something along the following lines:

A “right” is a moral principle defining and sanctioning a man’s freedom of action in a social context. There is only one fundamental right (all the others are its consequences or corollaries): a man’s right to his own life. Life is a process of self-sustaining and self-generated action; the right to life means the right to engage in self-sustaining and self-generated action—which means: the freedom to take all the actions required by the nature of a rational being for the support, the furtherance, the fulfillment and the enjoyment of his own life. (Such is the meaning of the right to life, liberty and the pursuit of happiness.)

The concept of a “right” pertains only to action—specifically, to freedom of action. It means freedom from physical compulsion, coercion or interference by other men.

Thus, for every individual, a right is the moral sanction of a positive—of his freedom to act on his own judgment, for his own goals, by his own voluntary, uncoerced choice. As to his neighbors, his rights impose no obligations on them except of a negative kind: to abstain from violating his rights.

Updated the plank.