In deducting from salary for unpaid vacation days can Missouri employer deduct at rate greater than what salary works out to be on an hourly basis for things like insurance, vehicle expense,and overhead and profit (which would be fixed costs regardless of how much the employee works)

An employee should receive advance notification (prior to the earning wages or when the reasons for deductions are incurred). It is strange for overhead to be charged to an employee. Your question is somewhat complicated. For example, if the overhead is to cover the cost of housing provided for the employer for the convenience of the employee, I can see where overhead may be deducted from wages (again, with the employee's prior knowledge). However, if the employer is trying to deduct a portion of the overhead of offices, for example, where the office would remain open whether that person is there or not, is "iffy".

That said, deductions for anything (within reason) are legal...with advance notice to the employee. Usually, such terms are spelled out in an offer letter.

Let me know if you have any questions.