Tom,
Not sure what you’re trying to accomplish here. I don’t know that a separate security agreement will get you more than a Promissory Note. Remember that a security agreement is just a contract. No contract language can supercede local, state or Federal Law (meaning you can not cause someone to waive their rights under the laws that apply).
Be sure you have your docs reviewed by a local, competent attorney before using them to keep yourself out of trouble.
All the best, Lyal