Burnwire design

Hi all. I’m trying to recreate the burnwire system utilized by the National Geographic Exploration Technology Lab with their deep sea dropcamera but at a low-cost, DIY approach. My setup is currently a delay timed switch connected to a 12v LiPo battery which is connected to the BlueRobotics High Power Cable and further connected to a waterproof cable connector for easy replacement of burnwires. The other end of the connector cable is modified to have a nichrome “weak link” in the center that will burn once the set time is reached. The rest of the ring utilizes silicone-insulated core to ensure that the nichrome bit will be the first to heat up. The prototypes of the burnwire look similar to this

The current setup seems to work alright in test trials but I don’t think the current setup can hold so much weight so it might snap before reaching the bottom and cause the camera to float before its intended time. Would you have any suggestions how I can make this loop better? Also, do you think the waterproof connector will be alright at 450m in depth or is it likely to leak/implode? I appreciate all your feedback.