That going into the deep part was a problem I never got around to working on, Making the edge zone into more of a pacman style teleport system where if you go up past the map zone you just loop back around to the bottom. Good Idea going out of bounds for safety, the enemy torpedos are programed so that they do have a range so you are in fact safe, good on you for breaking the system lol.
As for your idea to make it more of an active battle zone I don't think that is the direction of Sonar sight for the time being the current focus is to fix problems like you found first then work on an upgrade system rebalancing the map/enemies/player health and having more set stages. This games hinges on the sonar mechanic and if that was no longer a thing I feel like I would be removing a core gameplay mechanic. However in future builds of this game there will be changes to viewport and sonar speed and or how the mechanic works.
Thank you for the feedback!