This preprint develops a distribution-based framework for agricultural policy evaluation, using rice as a case study. It models joint distributions of farm size and age, compares alternative size distributions (lognormal, gamma, Pareto) with AIC/BIC/WAIC/LOOIC, and estimates productivity through scale elasticity and age effects. Nonlinear cost specifications with economies of scale are tested, and tariff-free viability is assessed under current cost structures. Scenario and sensitivity analyses quantify income vulnerability, while exit premiums are updated by incorporating age-linked remaining years. Results suggest modest per-hectare profits for smallholders, highlight the importance of mid-scale consolidation, and demonstrate that government outlays for exit support remain fiscally modest. The study emphasizes reallocating fiscal resources from competitiveness subsidies toward dignified exit and generational transition policies.