Heavy Air Mainsail Trim
I went back to the original message to review the parameters that were set for this question.
If you are above a beam and below a beat, then my guess is that the boom is going to be outside of the sweep of the traveler. Therefore, the effort of the mainsheet is going to pull the boom towards the centerline of the boat and induce twist to the sail. If I remember the sailing characteristics of most Hunters I have sailed, they have a tendency to weather helm. Depowering the headsail while at the same time adding twist to the main is going to unbalance the helm towards weather helm.
If the sailing conditions are as you describe, the boom end will most likely not be outside of the beam. If it strikes the water at that point, well, your day has gotten exciting hasn''t it?
Now with the wind on the beam at 20-25knts, I believe there will be some kind of sea running. In this beam to situation, there is bound to be some rocking and rolling going on. I have one scar on my forehead from a boom, and while it does add character, one is sufficient. When I am cruising, I am way to laid-back to want to worry about ducking a swinging boom.
Anyway, I feel that the great attraction of sailing is the test of each sailor''s ability to solve his/her problems. There are many right answers: Whatever works for you at the time you need it to work- that is the answer.