I will be decorating a wedding cake for my daughter's wedding in June. The venue is 200 miles away with limited refrigerator space. Can I freeze a carrot cake/cream cheese icing cake ahead of time and then let it sit at room temperature for 24 hours without all of our guests getting food bourne illness? The wedding is in northern Washington state so it is a cool climate.

no

That depends on the recipe you are using. This recipe has been tested by Food Safety Net Services and it qualifies as a "Non-potentially hazardous" food, according to the Texas Cottage Food law.

http://www.texascottagefoodlaw.com/Resources/Recipes/TraditionalCreamCheeseFrosting.aspx
 

Congratulations on your daughter's wedding! I recently got married and I made my own wedding cake, and got my mother to "assemble" it on the day of the wedding. I live very close to Northern Washington and we have the same climate, and  we were married in late September, so the weather was probably not that far off of June, maybe a little warmer. So your post reminds me a bit of my own wedding. 

That said, I really, really recommend that you make a cake that is safe to sit out for a few days. You are the Mother Of The Bride (!!!) and you are going to be very busy that day. I don't care how small or casual the wedding is, *trust me* it is going to be a big fun crazy busy few days. Stuff will come up. You want to make the entire cake as stress-free as you can, because you will find enough stress that day anyway. You don't want to be worrying if you are going to poison your entire family or be running around trying to find somewhere to keep the cake cool.

Don't forget that there will be leftovers that need to be stored as well, and you'll be busy with other stuff.  And around these parts June is usually not that hot, but it still can get pretty warm, especially in parked cars.  By the time you transport the cake, let it sit out on wedding day, and deal with the leftovers it will have spent quite a lot of time out of the fridge.

My favourite cake filling needs refrigeration, so for my wedding I did a different one. I don't regret it at all - by the time we'd served up the leftovers at the BBQ the next day a lot of time had passed. I'm glad I wasn't trying to find space for a 14-inch cake in a fridge, I was much happier socializing with my family! Trust me you will thank yourself if you make a cake that can stay out of the fridge.

You can use dry ice to keep the cake cold. Here's a link on how to do it. She also has another link on that page to her facebook page with even more details and pictures. You can also research it yourself for several other dry ice packing options. The main thing is to make sure you have your windows cracked a bit for circulation. Good luck! Be sure to let us know what you decided and how it turned out. Don't forget the pictures.

http://www.wedding-cakes-for-you.com/transporting-wedding-cakes.html