I have a cake to transport three hours away in the southern heat. It has cream cheese frosting . I am using Sugar Gerk's crusting cream cheese frosting snd wonder if adding meringue powder would make it more stable without affecting the flavor. 

Advice? Thank you!

Are you seeking stability, like holds together better, or stable to leave out more than 4 hours?  If the first, then more powdered sugar would make it more stable for uses like piping, although I wouldn't up the sugar for the overall frosting or filling.  If the second, then I wouldn't make anything with actual cream cheese.  There is an excellent recipe that uses while balsamic vinegar to mimic the taste but allow for a more shelf stable frosting.  It is an ABC , but it is possible that the concept might be usable for a meringue style frosting. That is here: https://www.cakecentral.com/recipe/61811/white-balsamic-american-buttercream.  HTH!

Thank you for linking the recipe, and I've saved it. For this time I'm making a cold box to transport.

I have a big problem, though. I'll start a new thread...

thank you, singer soul, for posting the recipe! I also just posted it before I saw this post -- ha!

but while I think I am late to this party, for going forward, instead of meringue powder use cornstarch to bulk up your icing when necessary --

take care