Just how big is this craft going to be?
Depending on how big and how stoutly built it is the requirements will change.
The size, weight and strength of the design would definitely have an impact on some of the concerns voiced previously.
If it is to have redundant systems as backup I would think it would start to get up there in size and start to create more of a hazard to other smaller (IE cruising) vessels, somehow I don't think a smaller craft built of composite materials would present much of a hazard to commercial
vessels. They've been known to run right over cruising sized vessels without even noticing......
Most of the safety
items mentioned like running lights, radar
, etc, etc are good ideas but do have power requirements which in turn require an ever larger vessel to carry them and the solar panels
needed to power them and recharge battery
banks. I certainly wouldn't want turn one loose without at least minimal visual/ electronic identification capability, it wouldn't be responsible; even though the possibility of a smaller cruising vessel colliding with it in the vast, open seas is remote
it's still is a possibility.
I'm all for your project
but think that there's much more to consider than just the ability to make it across an ocean, more like making it across safely without becoming a hazard to others.
I'm sure with some forethought it is completely possible, but I do like the idea of an automatic sinking option should all the propulsion
systems fail. If you look at some other threads on this site you'll see a number of cases of boats abandoned by their crews for various reasons floating around for months before beaching themselves fully intact; during which time they were a hazard to navigation. Otherwise you just have to decide what time of year your looking to let it loose and study the average weather
conditions to see what your little vessel will be in for.
Good luck, I'd like to see how your project