Thanks for everyone's input and interest.
I'm planning on doing open water testing on a small, normally very calm, lake I have access to.
In relation to prop to boat size ratio i how have the plans in CAD for a 54 inch hull and likely wont go over 3 inch diameter on the props.
For data Id like to collect: Motor amperage draw, Voltage across the motor, Motor RPM, shaft RPM (past gearbox) to characterize the power output. I want to use a GPS module to record position velocity and acceleration to characterize performance with different drive/prop configurations. Finally Id like to have temp and battery voltage red outs to monitor the health of the boat. Oh and a gopro mounted on the transom looking at the props

Since I last posted done a lot of research and looked into a wider range of product offerings. This is the power system up I'm moving forward with, as parts are in the mail or have already arrived.
Motor: SSS-56123 at 500kv, the longest can hobby brushless I could find. She'll put out damn near 10kW pulling 188 amps from a 12s source. The 188 amps keeps me from moving to a more expensive esc like a ZTW seal. There are motors that put out more power in a similar price range but there are a couple of factors that I think makes this one perfect for my application. The motor tops out at 25k rpm, this makes building a gearbox that wont explode much easier than it would be with some of the higher rpm brushless offerings. In addition the long case size, 10mm output shaft, and lower than average rpm tells me the motor is built more for torque than high speed power output. Granted this is still a brushless and ill be running a 3:1 reduction to get the most torque out of it.

Battery Pack: 5800 mAh 6s 25C zippy compacts. Four of them. Two series linked pairs connected in parallel. Each series pair makes a 5800 mAh battery pack that will give 12S voltage at a nominal potential of 44.4 volts. 25C rating means I can safely pull 145A from the pair. Then two of these units are linked in parallel giving me 11,600 mAh for max useful run time and way more amperage draw than I will ever need. This system was planned and purchased when looking at higher amperage motors so is kinda overkill for my choice of motor, but it shouldn't be a problem.

ESC: turnigy aquastar 200A. This is definitely the weak link in my chain but I was getting kind of intimidated with the 300 dollar ESCs. By its specs the turnigy should be able to handle what I'm doing here without letting the smoke out but I'm not super confident in it. If anyone has experience with this particular ESC let me know your findings.

I still need to solidify plans for a cooling system, transmitter and servo set up, and data collection/telemetry system not to mention hull, drive, and props. Silver lining of the current lock down is I have lots more free time now that I'm working from home.