I don't think I'd jump to rings too quick - you only have a few hours on the engine and the rings do need to seat. PCV valve is an inexpensive item and easy to change. Do you have a vent in the opposite valve cover? Also, you may want to consider a sealing/locking dipstick like this:

https://www.speedwaymotors.com/Lokar...ick,67748.html

There are a lot of vibrations in a boat so a different dipstick may be appropriate.

Thanks for keeping us posted - the video say a lot and is extremely telling.

Best,
Glenn