Do jumps outside the first 4k work as long PROVIDED they are jumps back into the first 4k? IE, could one locate a jump table at 0xFFF?
Yes. Quoting the FAQ:
One subroutine can dangle off the 0x1000 code RAM boundary if it doesn't contain any jump, jump0, or :call targets- try placing your longest branchless/loopless subroutine there!
0x1000
jump
jump0
:call
