This paper tackles the gain-scheduling control design issue when endogenous signals are selected as scheduling parameters. In this case, the gain-scheduled controller exhibits nonlinear dynamics, leading to the occurrence of hidden coupling terms in the linearized dynamics. Omitting hidden coupling terms in the synthesis process may induce performance degradation or even the destabilization of the closed-loop system. The present paper aims at extending a previous work on the design of gain-scheduled controller for hidden coupling terms inclusion via eigenstructure assignment technique. The efficiency of the proposed procedure is illustrated on a pitch-axis missile autopilot benchmark problem and is validated through nonlinear simulations.