I too have just read this thread with interest.
some years ago we were given a dog (border collie) from a back to back town house. We had a smallish kennel made for him, with nice cosy bed, (big enough for him to stretchout). that dog hated to come in the house, we had to be quite forceful to get him in when it was bad weather, and he was out again asap. Living in 'sheep country', soon after we got him I caught him chasing neighbours sheep, so he had to be tied up when outside.
I would say, the longer the tether the more problems likely to arise, the maximum mine get would be about 20+ft. and I've always made sure there is nothing to get caught up on, since that fella died, (cancer, a few years ago) I've often had dogs tied up out there, not on their own for 8 hours, and walked regularly, but when it's nice and I'm busy, they are safe and shout for me when anyone's about, it's nice to see them sprawled in the sun rather than fastened in a room inside. currently one dog is loose because I trust him, other one is tied when outside or she wanders off.
I would agree 8 hours on their own does sound a long time, I like 2 dogs anyway, and it sounds like the rest of the time they would be in the house? If there are 2 dogs and they are contained safely they should be company for each other.
After visiting a dogs home to get a replacent for original boy, I would think anything must be better than that place, I had to walk out at one point, couldn't bear to see all those poor dogs caged up. ('replacement' is the boy who can be now left loose in the yard). I did say he would be tied up some of the time and they were OK with that.