Will 8x6 be big enough for a run though? Assuming your hutches are at least 4x2 which will use up 16sq ft of floor space that leaves only 32sqft for the run.
Hi we're currently building a 9 x 6ft run for our pair and have used galvanised mesh. It's a good idea to put it on the inside of the frame to prevent nibbling too. Then you can always put a second layer on the ouside if you get worried about security. Make sure you use strong U-shaped staples to nail it in place, not a staple gun as a fox can rip the little staples out. good luck!