First and cheapest option is for each manager to have remote desktop access to their at work desktop. What if IT were to distribute desktop software to their at home laptops or PC. The server knows no difference if a file is accessed from a state away or from down the hall.
As far as QBO - you might not be happy with dat migration results and the cost is per subscription although managing them with a free QBOA account might be way to go. There are discounts for large number of companies but still you already own a you need other than access to it.
Somebody at the office with full access to every client file still has to upload each whereas sending files from office to home and each home user installing their second copy of QB at home is your best bet in my opinion
