You got some excellent advice regarding trimming for best efficiency but I ssupect you may be asking about proper trimming for rough conditions. In rough seas, efficiency and speed take a back seat to comfort. You'll want to run with the drive tucked all the way in (down) in rough seas and go more slowly. Keeping the drive down keeps more of the hull in the water and lets the finer entry (sharper angle) of the bow split the waves before they get under the flatter sections of hull, where the waves would make the boat pound. Your MPG will suffer dramatically in this state of trim though. Trimming down also lets the boat stay on plane at lower speeds. Trim tabs can make a huge difference in comfort on a shortish and wide deep V hull (like you have) They allow even slower cruising while on plane. They would cost a whole lot less than another boat and may be worth a look.
Here's a great article on trim etc.:
http://www.jerrylabella.com/on_the_level.htm