[SkunkBoat]

5/8" line is way too much. Bigger is not better.

Too expensive when someday you have to cut off (and your expensive anchor)...
You need too much room to store it!
300ft only gets you 60ft deep on a nice day. You'll be lucky to get 300ft of 5/8" in there.

3/8 ...7/16" is nice for pulling.

1/4" chain. 15' of 5/16 is too heavy.

That deck pipe will not fit chain. I have one in the 'never gonna use this" pile in my garage. You need the bigger round one or the oval one. I drilled a hole in deck and inside cabin to get to anchor locker. used a piece of cheap landscape drainage pipe siliconed between holes.

I saw a picture on the Mantis site of a Mantis in the same pivoting roller as mine.

here is a pic of the deck pipe