Well, if you want to do it the hard way, make sure that you remove your company drivers before exiting the game. You then have to rehire them when you start the game again ( a pain in the youknowwhere, i know )
Or, a easier solution, be the lone wolf, driving alone in your company. But be warned, loans rack up downpayments even if you're not playing, and you risk loosing your truck, if you got a loan on it, while offline