Straight to bed once your driving stint is done, no hanging around sitting in the passenger seat! Your mate will do same when his turn. Drive with the radio on but not too high, that way your mate can sleep through it easily. Avoid the sharp braking and swinging through contraflows and all will be happy…you don’t want him flying off the bunk or the partnership will be short-lived and you are likely to get your jaw rattled. Done it for a while back in the day and enjoyed it, money can be good and so long as your partner is descent then crack on.