I commend you on trying to start up your own business but I think you are asking for problems trying to convert this into your company tow vehicle. No matter what engine you put in the camper, you will most likely be exceeding the GCVW of this vehicle when towing even a small vehicle. since it is a business venture and you will be on the road alot, you are running a big chance of getting into legal trouble. If you end up on the wrong road at the wrong time, your setup with a trailer is either going to at best get you into legal problems with the law or at worst severely injure or kill yourself or another person.
you could find a diesel powered full size cargo van, you could convert it into living quarters and have a large towing capacity. I wish you the best success on your endeavor but check out the legal aspects of your endeavor. Make sure you have a business license and are bonded.
