You do not want to have an open topped hardening pen. The hawks and owls will clean you out. You must have a top on your pens or you will be doing no more than feeding predators. Five feet is also awful low, you will need a pen, normally called a flight pen that is high and long enough so the birds will be able to fly well before you release them. I recommend you visit a pheasant propagator and look at their operation and ask them questions so you do not waste a lot of money on something that will not do what you expect it to do. You can call the PA Game Commission Bureau of Wildlife protection at 717-787-5909 and ask for the permit division and get a list of pheasant propagators who are in your county or close to your county.