Free Ranging Advice Please!

Hi All

I have had three Black Rocks for a few months now.  They are in a run at the moment which I think they are happy in its about 10m squared. I would love to free range them which my partner has agreed to but he is worried by the lack of fencing around our garden and our pond.  He is in the garage now sawing away and swearing frequently as he is planning building a tunnel to part of the grass area which I have told him I don't want and it will look awful and not needed!  I can comfortably pick up the chickens now as they are quite tame and happy around me so I though I could get some stakes to put in the ground and use some nylon fencing/netting to make a 'mobile pen' that I could pop them into then dismount in the evening and move as required. My garden is very open onto fields so I would worry that they would wander off into the sunset unless I put up some protection for them.  An added consideration is my local pheasant and his wife who use our garden during the daytime for feeding and resting - would theycause any problems with my girls?  Any advice appreciated, I have looked for the netting stuff on the net but haven't found any. Thanks!