I bought 2 10x10 6' high kennels from a club member. I have cleared a nice shaded area in woods next to our house. I have 2 Labs that are house dogs and am just going to be using the kennel for keeping track of them during the day when our kids are in and out of the house. Without pooring a conrete pad, what is an economical solution for the floor of the outdoor fenced area?? Is stone/gravel a viable option? If so what size stone...smaller better? Any ideas?