Everybody is going to give you tons of advice, and most if it very good. Sooner, or later you will be in WEATHER. Not the good stuff, but the kind of stuff where you want to hang on, and most likely it will be wet.
On my cat the P.O. put in a special piece of wood at the rear of the house's roof. You can see it right in front of my wife's nose. This wood is indented in the forward edge. Here you can get a good grip to let yourself down, or pick yourself up. The indentation is nearly half the size of the thickness of the wood.This ridge also prevents water from coming over the edge like a gutter.
BEST WISHES in making your boat as close to, or even perfect for you. I love my boat, but if, or when I ever build my own boat. I know there are things I will tweak to make her safer, and better.
I do keep one of those plastic chairs that look like an Andaronick chair in my salon
. I use cushions
to make it VERY COMFY