Thanks for all these suggestions. I'm crystal clear now as to how I will go forward. I'm always on a motor boat - chasing my subjects who are sailing and rowing. This means I'm always near the drone ( half mile at most ) Will keep an eye on battery and land, manually, back on my motorboat when battery gets low. Change battery and keep on going... I will be turning off the automatic RTH and I will also change setting to "hover if lost signal". Although, I'm with the drone always so i'm thinking this is over kill.
I did purchase pontoons - not to intentionally land on the water - but because weird things happen and I want to get it back if it decides to land without my permission. (perhaps I stretched the battery too long...)
Again, thanks for this help - VERY HELPFUL!