Overtime during a commission period

Hello,

Great product, overall very functional. One thing i can't figure out, though, is how to plan for periods where resources have to work overtime to complete an task within a fixed period. Typically this involves a service engineer that has to travel to a remote site for commissioning, and has access to the factory during a set period, i.e. two weeks. During this period the engineer typically works 12 hours+ per day, but never more than the quoted amount of hours the client has paid for. If I allocate the quoted amount of hours into the resource allocation for the task, the planner will prolong the task period to "expend" the hours using the normal working hours (7.5h), which is logical, but in my scenario not what i really want it to do, as the engineer only has two weeks access to the factory.

What is the recommended way of handling scenarios like these in ProjeQtor?