Hi @LeviRumohr15, welcome to the forum 
Using BlueOS you can easily set up multiple streams (just configure them in the Video page), and there are some options covered here for receiving them. The main limitations with extra cameras are
- bandwidth usage (can be problematic over a long tether)
- decoding at the topside computer (may require a lot of processing power, depending on resolution and frame rate)
- port availability (a Raspberry Pi has 4 USB ports, and in our vehicles one of those is generally taken up by the Pixhawk flight controller, and others are frequently used by other peripherals like sonars)
- it may be possible to work around this with a powered USB hub to one of the USB-3 ports on the RPi 4, although with lots of peripherals you’ll need to take extra care to avoid the electronics in the enclosure overheating