Sounds like another UPS/FEDEX in the making haha. Which by the way both of those companies require you to have to Flight Engineer (FEX) written to apply for the job. You would need to get some hours, what would probably be best for you is to instruct since you already have a business. So definately get your CFI certificates.

Flying cargo would be a good option since that is what you are already involed with. You could look at Welcome To AirNet Systems, Inc. they have a pretty good program as far as flying cargo. Most, if not all, cargo carriers require that you have about 1200TT also.