We study electron transport through a monolayer jacutingaite (Pt₂HgSe₃) tunnel junction in which only the barrier is irradiated by off-resonant circularly polarized light, while the leads remain undriven. In the high-frequency regime, the driven barrier reduces to an effective static Dirac Hamiltonian with a photon-dressed, valley-dependent mass term. A staggered sublattice potential V_z and a substrate-induced exchange field mₛ provide additional tunable mass terms. Using scattering theory, we compute spin- and valley-resolved transmission and reflection, as well as the Landauer conductance. Photon dressing shifts the barrier Dirac masses with opposite signs in the (K, K') valleys and induces a splitting of the propagation thresholds. The finite barrier then produces channel-dependent Fabry–Pérot-type interference through the phase qₓ^(η s_z)L. We find broad parameter windows with near-perfect valley filtering (|Pᵥ|≃ 100%) and substantial spin polarization (|Pₛ|∼ 70%). The dominant spin and valley polarizations can be switched by tuning the drive amplitude A₀, V_z, and~mₛ.