I fully the understand your need to note your ancestry. As has been previously stated Small Ship registry is UK and with only a few expections you must use the red ensign.
I decided to add the Saltaire to the bow.Subtle but sexy...Like its owner
. Actually there is not many other alternatives...However,
I was back in Scotland last June and watch a boat beat out
of the Sound of Sleet and it had a tartan pennant... presumingly his clan and years ago there were quite a few flying their Clan Flag. The latter will be easily purchased, the former will need a little research
Anyway...Now we know where your articulate pragmatism is sourced...