In this paper, we present a joint transmit antenna selection (TAS) method and power control strategy aimed at enhancing the performance of spatial modulation (SM)-based wireless systems supported by a full-duplex vehicle (FDV). We analytically derive closed-form expressions for the energy efficiency (EE) and symbol error probability (SEP) of the SM-FDV architecture under TAS and validate them through Monte Carlo simulations. Building on this, we develop an optimal transmit power scheme for the FDV to simultaneously improve EE and reduce SEP. Numerical results confirm the clear superiority of the FDV over its half-duplex vehicle (HDV) counterpart in terms of EE, regardless of whether TAS is applied. Additionally, integrating TAS significantly boosts EE, lowers the required transmit power, and achieves better SEP performance compared to non-TAS configurations. Under high residual self-interference (RSI) induced by full-duplex transmission, system performance degrades considerably, prompting the introduction of a power optimization approach tailored to such interference-heavy conditions. This approach not only mitigates the effects of RSI but also reduces the negative impact of other critical factors, including FDV mobility, altitude variations, and elevated carrier frequencies in the millimeter-wave (mmWave) band. Further analysis examines how parameters such as data rate and the number of antennas influence system behavior. The resulting insights offer practical guidance for optimizing SM-FDV systems, both with and without TAS.