Ardupilot equipment recommendations for autonomous ASV

Hello,

I a total newb and basically have no idea how to proceed. I run a small NGO in Guatemala, trying to restore Lake Amatitlán (amati.org.gt). I was given an old non-working SeaDoo XP (1980s) and would like to turn it into a data gathering drone. I am planning a suite of instruments including a depth sounder, temperature, oxygen, pH, clorophil sensors. I will be using a couple of 30 lbs thrust trolling motors for power and differential steering, everything hooked up to 1 or 2 12V 100Ah Lifepo4 batteries. Can you recommend Ardupilot equipment? We have a very tight budget, all help greatly appreciated!