If it’s a night run traffic shouldn’t generally be a problem so I would just get on with it. If you need a 45 on the way down, take one. You have two 10h drives a week so it can go wrong 2 days out of 5 without any danger of you breaking driver’s hours rules. If you run out of driving time half an hour from the yard on the way back on the other three days they’ll have to send someone out to fetch you as the chances are you’ll only be half an hour or so away at most so they would be mad to ask you to have 9h off and then run in.
If it turns out that they have to come and fetch you on a regular basis they might rethink the whole thing and change it to something more sensible.
Paul