Jumbo Cupcakes Filled Cupcakes?

Filled Cupcakes? - jumbo cupcakes

I have a lunch at the end of July, where I will feed about 150 people. I want to prepare huge cakes filled with cream cheese frosting. I'm on everything good except the garnish. The recipe I have the Key Lime filling. It fabuolus but I do not know how the idea that a sufficient number of lime juice for many small cakes. Ideas for other surfaces? I had two different toppings, such as, if possible. I thought I could frosting cream cheese on one and maybe a chocolate ganache on the other.
Thank you!