Thats a shame its a great little kit !!,
what i would have done in that situation would have been push the parts back out best i could to shape and tacked the breaks with super glue, and 'holes' i would have patched internally with some plastic card and made external patches to try to level up the surface then add some body filler, this reduces to amount of filler needed to seal the hole and also reduces to cracking that's will occur with body filler if the hull flexies at some point.
Any surface bends and cracks do you best to repair inside to seal the boat and yet again more body filler on the outside.
in situations like that i would also look at adding internal bulkheads around those points if possible to reduce the stress on the weakened parts of the hull..
not much else you can do other then just keep at it. but i'ld like to see the repair photos!
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