Borders are a difficult one, even whe not on a road side. I tend to treat it as long as the warren is partially on your land, do the whole warren, but no further. If you know where the farm is/owner is, then by all means, go ask for clarification, you never know they may give you the rest of the land as well. As for the road side, I would crack on, as long as you're respectful and clean, and not running round like lunatics causing chaos on the roads, you'll be fine. As I said above, stick a high vis on and nobody will question that you shouldn't be there.