Think hard about trim: how should the boat sit best in the water to encourage movement? And how can you achieve this within the rules of racing?
As a rule of thumb most weight in ultralight breeze should be to leeward and as low down in the boat as possible. Modern wide stern yachts have a large wetted surface area which creates drag in very light winds so benefit from weight forward. More traditional shapes prefer weight in the middle.
Most of these changes will need to be made by moving crew weight around. Be specific about where you want off-watch crew to sleep and don’t be afraid to ask them to move if conditions change.
Ensure that all movements around the deck are gentle and slow to keep any momentum you may have gained.
If your racing class allows the movement of equipment as well as crew, then put the effort into stacking gear in the position where the weight will have most effect.
This can be hard work in hot and sweaty conditions but will pay dividends.