hmmmm. good question. For the first part Id say yes, just the one guy. But to the second part where you are advertising your "service". No. Thats holding out to the public. Now if that guy tells his friends, and they contact you then splitting the costs I think is ok. Them paying all the costs (whether they pay your or not), no. Thats not legal unless u have a commercial. (this is my opinion from what I understand, I may be mistaken, correct me if I am wrong)

If the other companies had guys who were pilots(recreational or commercial, doesnt matter) on staff that went with you then you could get a free flight, if the company compensated their employee for all costs, and he/she let you fly it while they take pictures or whatever. It would be incidental to the other pilots business. So all costs can be covered by the business. But that is one big gray area... the FAA doesnt clearly identify what "compensation" is considered for you. Is it lunch? Flight time? A ride to and from the airport? or just a pure and simple paycheck? They all have a monetary value right? Hard to tell for sure if this would be legal.
Maybe a FAA guy could chime in here. How do you see this situation?