You're just going to have to mask off around the broken truss rod screw, then dig in around it until you can get some needle-nosed pliers in there to turn it and remove it. It's going to be a bit messy but you can repair it. Hopefully all the mess will be hidden under the TRC. If not, you can always make a slightly bigger TRC to cover it up.
I can't quite get behind the headstock shape on these kits. I'm bang up for something wacky, but it needs to suit the guitar, I reckon this one needs more angles and corners.