There's a lot of good suggestions here. I like the drilling relief holes at the ends of the crack. That will stop any additional propagation of the crack. I did that on my motorcycle windshield and it worked great for years till I sold the bike. After you repair the outside you might want to add additional repair tape on the inside for additional protection. I understand your thoughts on repairing the skylight but I got the impression that you think it will happen again. If that's the case then maybe you should be looking to add a branch guard around the skylight or you'll be revisiting this issue many times. Good luck on your repair I hope it all works out for you. Why don't you post a picture after your done of your handy work for others to see.
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