You would be correct on the liability of insurance. A truley licensed guide (in some states) are required to have a captains license before they can accept monies to take people out on a boat. With that said, most boat insurances specifically state "not for commercial use". Hence the reason the quide would use his boat. Because he is licensed and insured. Using someone elses boat, it would not be insured correctly.
That said, many guides are prone to work one specific area. Take them out of their element (their home lake) and they are a little above average in comparison to most others. I woudl say your best bet is to find someone from this site that is a good fisherman, that understands structure, what fish do at different times of year, maps etc... Have them come out for a day on the water (in your lake). Make sure they are knowledable of YOUR equipment. I can walk people through about anything on a lowrance unit but would be a fish out of water on an HB unit.
If it was me, I would look for a tournament guy. Unlike a guide... these guys travel to different lakes all the time. Pick their brain on how to tackle a new lake. How they read maps, and depth, and structure. Many guides attempt tournament fishing only to fail simply because they are mainly concentrating on their home lakes and have learned them well. I have many buddies from Lake Michigan that are charter captains. They put people on fish day in and day out. Put them on a boat in Lake Huron and they are out of their element. Same fish, different body of water.
I have OCD "Obsessive Crappie Disorder"