$300 or even $500 may seem like a lot to spend on an old hull. But if you consider this as an investment, it may well be justified.This Sunfish is nearly 50 years old, so $300 for materials to Do The Job Right seems like a questionable investment and is much more than I want to spend.
Plan B will cost <50 bucks, so worth a try. If I go with Plan B and the repair doesn't hold up well I promise to post again and be an example for others!