Will your new constitution protect my right to have a contract with anyone that says anything, or will that right be limited somehow?

Here's what TC2K says in Article 3, Section 4:

"The obligations of contracts shall not be impaired provided only that all parties to the contract entered the contract knowingly, willingly, and voluntarily."

So the answer to your question is that the only limit on contracts is that all parties know what the contract says and that all parties enter the contract willingly and voluntarily. If those conditions are met, then you can have a contract with anyone that says anything. Of course, if the contract requires one party to commit a crime, then that party will still be responsible for the crime. Other than that, go for it.