Having a business that have mobilized employee is not that easy at all. There are lot of things to be considered, I mean and every step of the employees must be carefully monitored like if they are doing their job properly so a customer will be satisfied. Another is their expenses, having a constant monitoring about their expenses is not that easy to do. Like for example their Car Allowance, there are too many factors that affects a vehicle. There are the applied taxes on different places that causes variable cost on gas, tickets, maintenance, etc..
There are solution for this problem, the first would be adding another department in your company that will do the report expenses of the mobilized team. But the problem is, it is not advisable to hire another group of employees only to do that certain task. It way out of the business, eventually will cost the business too much. A company called Corporate Reimbursement Service, Inc. (CRS) provides a solution that will let you know everything that are mobilized, like their expenses, maintenance, etc.. Trust is there, because these guys are professional on such services rather than hiring another group of employees that will start form scratch.