The one with cargo having to be full is a good one, you'd have to have people onboard watching the cargo number, might be interesting because sometimes you get lots other times it's like one crate
But then you'd have to decide whether it counts if you sink it with someone else who's in the race too, or is it first come first serve lol. Also the bigger your ship the slower it is, but the faster it will sink passing ships to fill cargo, but the little light sloopies however may take longer, but are generally faster. lol Interesting to see ship choices or whether it's all the same.