All the advice about a owner survey
and contacting the oem and other experts is excellent. I repaired several fiberglass commercial
hulls and a couple yachts when I was younger. I never patched from only 1 side. However, if you make the patched area too stiff in a flexing hull
, you can get other failures. It's not as simple as a big inside patch.
Remember, your loss also includes diminished value. In the future your vessel will appraise lower forever because of the patched damage unless it is hidden (not smart).