If you are wanting to do this for meat rabbits I would say you have a good plan. I would however maybe plan to build or buy a few hutches, you could then keep a trio in the hutches, a buck and two does, letting them run seperate in the run, or the girls together if they got along. This way you would still be able to control breeding, know when babies are due, have babies born in a nest box in the hutch, but once they are weaning age 6-8 weeks, you could put them in the "cube" I think that would be plenty of room for even 2 + litters of young rabbits.
Problems I see that you will need to think about before hand
1. Some rabbits get along, Some don't, some bucks can not be with other bucks, others are okay. I would deffinatly only go with one buck though. One buck and two - 4 does with enough meat for your family plus some to give/sell to others.
2. If you have them all running loose (if they will get along, I would say there is plenty of space) you won't know when a doe was bred, when her babies will be born, or be able to keep the buck from immediately re breeding your doe. It will also be very difficult to keep records of which doe had which babies, as they only feed them twice a day and good luck notice which is the mother. Plus if there born close to the same time, once they leave the nest you will be hard pressed to tell who's are who's.
3. The buck or other does, could kill the babies if they are all kept loose together. I have had two does (unrelated) that got along well, they lived in a 9' by 3' cage. Introduced to each other as adults. The rabbits we have now would not be able to do this, they are much more territorial and most can not be let out together even in a large area like our back chicken pen. These two does did get along great, they had litters about a week apart and even with the age difference, once they where out of the box we couldn't tell who belonged to who.
4. Foraging- they will eat the grass, depending on how many you have, they may eat all the grass, but even if they don't you will need to supplement with rabbit pellets, and they need to have hay available to I would think.
All in all if you think it out well before hand I think you have a great area that you can use for rabbits. I would recommend buying young rabbits (about 8 weeks) if you plan to keep them all together. They get along better at that age. Also think you should really start with just three- buck and two does, and include some cages/hutches so you can separate the buck from the does most of the time.
