As long as you enter from the windward side, you can pull yourself right into the cockpit in 2 seconds. I'm 190 lbs and I've never fallen backwards while entering. The most important issue with Sunfish is to have a bunji on the dagger board. If it falls completely out while turtled, you have to dive and search for the board and insert in the bottom to right it.
To gain some confidence, purposely flip it in water not over your head. Then " practice" pulling yourself aboard without touching the "lake" bottom. Then when you take a drink unintentionally, you'll have the experience already tucked away.
Remember...windward side is your friend.
Sailing is all about communication and teamwork. A lot of
videos show two people each doing their own thing when trying
to right a boat. It's also how they most likely got in the situation
in the first place. How many canoe's have you seen with two Indians
and no Chief. Teamwork -Teamwork -Teamwork makes the pointy
end go forward.