In reality, during this time, the loaders are not engaged in loading but are essentially passengers. Nevertheless, these hours must be paid for, as they are spent on the transportation services.
It is permissible to pay the movers after loading according to the rate and hire another team for unloading. However, this approach may lead to some issues: there might not be qualified personnel at the unloading site. Finding movers could take a lot of time and might end with you not finding anyone for the job. This happens frequently, especially when people are moving to a new, unfamiliar area. Therefore, it is better to play it safe and bring a team of movers with you to avoid problems and ensure the unloading is done properly. Improvising on the spot can result in a waste of precious time and nerves. It is up to you to decide what is more important for you.