I’m delighted to hear that your cake turned out beautifully! Good for you!!! Now we want to hear how it’s received - they’ll love it, I’m sure - and also when you can spare the time to try posting pictures, it would be great to see.
Posting pictures is much easier than it looks. Just scroll down on the post a new reply page to where you see an option for attachments. Click on the word Browse, and that will bring up a Microsoft choose file dialogue box. Use that box to find the image you want to post. Click on the name of the image, then on Open. Lo and behold, the image is selected for posting and appears in the attachment box on the forum posting page. If you happen to be on a Mac, there’s great advice in a thread called - of all things - A Rye and Some Cheddar that I found by searching the forum with the words posting pictures.
But that’s for the future. Also when you get a chance, I’m curious if you measured the coconut by weight or by volume and before or after toasting. I’m really interested because I, too, would use an unsweetened dessicated shred. I have 2 1/2 kilograms of the stuff bought for a job that didn’t pan out!
Regarding the temperature concerns, Rose says elsewhere in the book that ganache can be held at room temp for up to 3 days. She only suggests refrigerating briefly after frosting to set the ganache, and then you can smooth it with a hot metal spatula all around the sides. The cake itself and the filling should be good for at least one full day at room temp. My guess is the same as yours, that the cake would best served at room temp. However, I see that Rose says this cake stays soft even when chilled. You could leave it in the fridge until a couple of hours before leaving?
Enjoy your triumph this evening! It’s well-deserved.