Well im city gal and im a anti off leash person . My 14 front acres are fenced.
So I dont suggest that to anyone.
Being a giant breed you wont get the speed for take off.
They will bond to you and with training anything is possible.
You set boundaries by NEVER extending your walks beyond a safe zone.
So you do not take them on road for a walk if you dont want them to go there and go walk about without you. Once they mark the territory as theres then when loose it is their job to walk the edge of the property.
I learned this hard way took my 1st CAS 13 years ago out to post my 50 acres on the edge.
She was loose with me on my middle 10 never front or back.
Next day let her loose and did my reg walk and she took off down the same path she marked the day before . I ran to house to get the car she was back in a flash.
Next year find out from neighbor behind me that u should of seen the Rottie mix that came out your ditch with a orange vest She Stood her ground would not let him close to the property line. She postured mock charged dug a hole like to bury him it he then told her go come girl ( I was screaming and she heard me). So she saw no threat and came home. But her growl and posture is far worse then any bite. Since they put so much into displaying to ward scare off strangers it is like the demon from hell.
She was NEVER let loose again. And none of my other dogs even know I own that much land.
So each dog is different if you get the correct pup for u no limits to what you want to do.
you can train a 4 ft perimiter for walking and recall every time they go too far.
Other than being carefull with giant breeds. Slow growth , make sure food is approite to the exercise , Glos/Chrointin/ carefull about bloat dont know about it but heard it is deadly.
Think you will be great no matter what you choose.
My wish hit lotto fence in all 50 acres