ccx2,
Don't think for a minute this is the same as the dive shop pool. If you're pulling the flag how do you feel about getting entangled in your own line? It can happen faster than you think.
Unless your flag can carry spare weights it will be a lot easier dialing things in while in a pool. Especially so when you drop a weight in to the silt.
At the end of the day I assume you're an adult and you are a certified diver. I agree a shop pool can get pretty stinking boring real fast and burning a tank may be painful. None of us have a sense of your present skills and understand that body of water as you do. Having a spotter is a good idea but depending on circumstances they may not be able to effect a rescue. Listen to that little voice in the back of your head and if you do the pond stay focused.
Pete
Did he say anything about pulling a flag? Maybe I missed it. May not be a lot of boats in a pond with a max depth of 12ft. If it is only 12 ft he could easily know if it is free from obstructions by having swam in it.
Having said that, I do not endorse his idea.