@pockketz yes its possible, make sure you create a new folder for your combination and not overwriting existing files. Copy the file "simple.xml", the "art" folder, and any other lose file in the Tronkyfran folder to the new folder, then copy all the folders (except art folder) from carbon to the new theme folder.
It looks like the paths for those two themes are the same, but expect many parameters to be off, such as text and images being misaligned. So you will likely need to read up on themes here https://github.com/RetroPie/RetroPie-Setup/wiki/Creating-Your-Own-EmulationStation-Theme