Maximally Natural Supersymmetry, an unusual weak-scale supersymmetric extension of the Standard Model based upon the inherently higher-dimensional mechanism of Scherk-Schwarz supersymmetry breaking (SSSB), possesses remarkably good fine tuning given present LHC limits. Here we construct a version with precision $SU(2)_{rm L} times U(1)_{rm Y} $ unification: $sin^2 theta_W(M_Z) simeq 0.231$ is predicted to $pm 2%$ by unifying $SU(2)_{rm L} times U(1)_{rm Y} $ into a 5D $SU(3)_{rm EW}$ theory at a Kaluza-Klein scale of $1/R_5 sim 4.4,{rm TeV}$, where SSSB is simultaneously realised. Full unification with $SU(3)_{rm C}$ is accommodated by extending the 5D theory to a $N=4$ supersymmetric $SU(6)$ gauge theory on a 6D rectangular orbifold at $1/R_6 sim 40 ,{rm TeV}$. TeV-scale states beyond the SM include exotic charged fermions implied by $SU(3)_{rm EW}$ with masses lighter than $sim 1.2,{rm TeV}$, and squarks in the mass range $1.4,{rm TeV} - 2.3,{rm TeV}$, providing distinct signatures and discovery opportunities for LHC run II.