We investigate the electronic structure, local orbital coupling, and strain-tunable nonlinear Hall response of two arsenic-substituted borophosphene-derived monolayers, As@MBP and As@AMBP, using first-principles calculations and tight-binding analysis. In the absence of spin–orbit coupling, both systems exhibit a finite Berry-curvature dipole (BCD) and a substantial nonlinear Hall conductivity, demonstrating that the nonlinear response is intrinsically driven by orbital physics and inversion-symmetry breaking. As substitution opens sizable band gaps of 120 meV in As@MBP and 90 meV in As@AMBP, well exceeding room-temperature thermal fluctuations (k_BT ≈ 25.9 meV). Tight-binding analysis reveals that As incorporation breaks the equivalence of B-P hoppings in As@MBP and induces sign reversals in key nearest-neighbor hoppings in As@AMBP, reflecting a pronounced electronic reconstruction beyond simple geometric effects. Under mechanical strain, the redistribution of Berry curvature yields a maximum BCD of 22 mathringA in As@MBP, approximately 10 times larger than that of unstrained structure, and induces a reversal of the BCD sign. These results establish As-substituted borophosphene derivatives as promising light-element platforms for mechanically switchable nonlinear transport and quantum-material applications without relying on strong spin-orbit coupling.