Silver Fox rabbits are beautiful...i have never personally had any, but have always admired them.
I started by keeping my rabbits in cages, but i hate to see any animal in a cage, so i moved them to a colony style free range. It is very expensive to build a rabbit proof free range house, but they love it! I still have some boys in cages part-time since they fight. If you are planning to give them access to grass, the only thing that keeps them in in my experience is digging up the entire area about 1 foot down, laying fencing down, then reburying it. It is hard, but they like the grass. I made a couple per pen so i could move pastures and give them fresh grass.
I also feed them naturally. I pretty much grow all the food they eat (except for the hay, i don't have enough room for that. I free feed hay, and they also get various lettuces, cucumbers, herbs, carrot tops, beet tops, celery greens, etc. They also graze during the day. I grow corn, wheat, and oats to give them as a supplement to hay during the winter. They also get herbs and some other veggies during the winter if we have extra.