Thanks for the info Grant! I have since ordered all those items along with a few other things as well. I have all winter to get everything laid out prior to testing in the spring so I presume I will be ordering a few other items as well.
Good to know once it's programmed with Mission Planner it can go until it's completed the mission, run out of fuel, batteries or anything else catastrophic. Haha.
Thanks for the info on the cube, I have seen so much documentation for the PX4 it should help flatten my learning curve a bit. Once I get used to it and find limitations then I think I'll be ready to upgrade.
On the boat I plan on running a Humminbird fishfinder, 798CI HD SI (one that I already have) and will be recording the data to the SD card within the unit, however I want redundancy in that data so am now adding a Raspberry PI3 to load mission planner onto as well as record the NMEA data from the fish finder. The Pi doesn't have enough processing power to run Reefmaster, however I was thinking of an XBee-Pro 900 XSC S3B Wire (https://www.sparkfun.com/products/11634) to possibly SSH (would that be possible?) into the Pi to edit or monitor the Mission Planner progress. Also to relay the NMEA fish finder data to my laptop on the shore which would be running Reefmaster. So I could see in real time the map being generated from shore, but if there is a break in communication it'll still be recording to the fish finder as well as the PI onboard.
Would the XBee-Pro 900 XSC S3B with a Pi offer more control than the RFD900 radio?