Nice write up! Evidently you have a good sense of humor as does your wife.
Is this the boat you got? MUTINEER 15 sailboat specifications and details on sailboatdata.com
To answer your question about tipping the boat: Yes, you should have let the main sheet out, all the way if needs be. You should also develop an instinct to head the boat up into the wind during gusts when you feel it starting to heel too much. The boat will not tip over if no wind is being caught by the sails. Both releasing the sheet and heading up will keep the boat on it's feet.
I'll agree with you on your assessment about mounting a motor on her. Neither an electric motor or a gas engine would like getting dunked in the drink.
I'd make sure you have a good paddle and a small anchor with you at all times. When the wind dies these can be your friends. When there is wind you will need to be able to sail the boat to your destination.