Model Predictive Control: Hard constraint at fixed moment in time (set terminal)

I'm currently implementing a MPC controller for a MIMO (5 inputs and 8 states) system. I need a hard constraint at a fixed moment in time. Let's assume at 20sec (with a simulation time of 40sec, Ts = 1). A solution is to define a reference track to that point. However, the cost function is therefore related to the deviation from the reference, which is not desirable in my case. Another solution is to use the 'setterminal'. This command provides a penalty weight at the last step(s) of the prediction horizon. However, during simulation, this penalty weight matrix needs to adapt to meet the fixed constraint at t=20s. For example, at t=1, the penalty weight is at the last step in the prediction horizon, while at t=5, the penalty weights are at the last 5 steps of the prediction horizon. Is it feasible to implement this constraint using 'setterminal' or is another command/function more appropriate?

Thank you.

Leon