> I wish there was a way to specify the offset base with something like a C #define or compiler directive.

Julia has OffsetArrays.jl implementing arbitrary-base indexing: https://juliaarrays.github.io/OffsetArrays.jl/stable/

The experience with this has been quite mixed, creating a new surface for bugs to appear. Used well, it can be very convenient for the reasons you state.

  julia> A = collect(1:5)
  5-element Vector{Int64}:
   1
   2
   3
   4
   5

  julia> B = OffsetArray(A, -1)
  5-element OffsetArray(::Vector{Int64}, 0:4) with eltype Int64 with indices 0:4:
   1
   2
   3
   4
   5

  julia> A[1]
  1

  julia> B[0]
  1