I just did quick test.
Compiler doesn't mind compiling code larger than 128K. Actually, there is no way that compiler could know hex size, before assembling. So far so good.
But after assembling, assembler returned error that generated hex is too large. After adding __MAXROM 0x1FFFF to P18F67K22.inc, hex file is generated without any error.
I have done "secure" bootloader for PIC18F67K22, so when I need more memory, there is simple solution.
Thanks, tumbleweed!