I ran across this tutorial on how to disassemble a D5300 to remove the hot mirror filter. Importantly its the only disassembly instruction set i could find. It should apply to the D5500 and D5600 as well. You would need to get a clear UV IR Cut filter from Astronomics of the right size to make it full spectrum, which would go in place of the IR filter shown in the tutorial.
https://www.lifepixel.com/tutorials/...rsion-tutorial
I am not game to mod my new camera right now, but someone might want to try it.