As someone with not only extensive knowledge and experience in Docker and Linux, but also a strong networking administration and systems administration background, I'm well-equipped to tackle your project. Over the years, I've garnered invaluable experience working with Mosquitto brokers in bridging them on various platforms, a skill that aligns perfectly with your needs.
Additionally, my experience with AWS EC2 is sure to come in handy as I'm deeply familiar with managing these containers even at the server level. This means that I can modify and configure the instances to accommodate your needs without any hassles. Furthermore, my understanding of high availability configurations is a huge plus for this project which requires smooth handling of a high demand environment.
Lastly, though there isn't a specific security component for this task, it is still essential to build a solution keeping contingencies in mind. Being proficient in Linux makes me extremely information security-conscious - reliability and trustworthiness is of utmost importance when working with your data. Considering my blend of skills and expertise, à la carte for this job is definitely a bet you won't regret taking!