There's no better way to increae rabbit numbers than with brush piles. There is lots of advice from game agencies on the net. I've used old skids, cut trees, tires, etc. anything they can get under to escape predators.
How many acres are you fencing? If it is currently pasture, it may be too small. But then it depends on the kind of trials you are planning. Brace trials would take less area than "little pack."
What kind of grass is the pasture? Fescue is toxic to rabbits. Here in Michigan, timothy, alfalfa, orchard grass, brome grass and red clover are all popular. You'll need nesting areas, winter foods--berry canes, sumac, and other small shrubs--overhead cover, and escape cover. Old fields reverting to shrubs and brush is excellent habitat.
What kind of equipment do you have: tractors, planters, brush hogs, disk, etc? Disking or spraying alternate strips is a good way to get diversity. Disking brings up dormant weed seeds.
Posting pictures of your property would be helpful.