I love a flag
I mounted my flag in the hole used for the mast crutch you use for trailering. I found the chrome recessed flag holder, the flag and teak staff at West Marine. You have to measure the diameter of your own particular mast crutch hole, but WM has a number of different sizes. You have to remove the holder naturally when you need to put the crutch back into trailer, but the location and ease of putting in and out are perfect for my situation.