How stable would set royal icing be in high humidity?

I left bagged cookies (tied tightly with ribbon) in a hot car for a day. They had a lot of condensation on the inside of the bag and the frosting had what looked like what people think of as butter-bleed.  I thought they were ruined but I took them out of the bags and dried them in front of a fan and they were as good as new.  I rebagged them and they looked and felt perfect...for what it's worth!

Thank you! That does help a lot. If it was me travelling I could factor that in and re-bag them, but that'd be a lot of hassle for the customer. Thanks for your help :-)

I was at a vendor tent last weekend, and soon I was in the position where all of my cookies were in the sun.  Major condensation on the insides of the bags.  I though all was ruined.  I packed the cookies at the end of the day, and that night took them out of the box, and Most were OK.  No condensation in the bags, and only those with black icing had been ruined.  The next day I only put out a few cookies at a time, and moved them alot to keep them as out of sun as possible.

I live in a hot place, but humidity is not all time present.  But when there is some humidity I use a bit of crémor tartar in my royalicing récipe and the help of a dehidrator and fans for the cookies, but if the humidity last more days I have lost some batch or cookies, so I look at weather channel to know when must I do my cookies.   For decorated cookies I have no problema in wet weather, I put them in metal boxes (where the danish cookies come) and if I am a bit worried I cover them with plastic bags the box and I have had no problem.  For me the problem is to decorate the cookies in humid weather.