It has been standard procedure for many years to start one-design fleets of the same general speed together if they are small fleets. So that is not an issue. And if you take finish times on all the boats, it is not a problem sorting them as individual fleets and as an overall Portsmouth fleet for that whole start.
But nobody has answered my initial question as to tactics -- If you are going for trophies in both overall Portsmouth in that start group and for trophies in your one-design fleet, how do you decide whether you are racing just your own one-design fleet or racing for the overall Portsmouth trophy or both?
And I have an additional question as to how reliable the times and results would be as far as inputting for Portsmouth ratings. Obviously, if you are racing within your own one-design fleet, you are not going for fastest time a la Portsmouth, you are planning your tactics to beat the others in your own fleet, and time is not important.