? I've seen boats with young kids that have safety netting run on the life lines.....I'm thinking netting is no substitute for a PDF, underway or not.
Absolutely NO substitute.
PFD (Purchase at home, one that fits and comfortable.)
Rash Shirts WITH a collar or a gaiter to prevent rash... If rash, then uncomfortable>>> then won't wear.
We did this with our kids starting ages 3 and 7.