I guess I have been there, done that before. I have been heavily loaded, and take all those chances to stay well back from frontal collision, don't get mad when they cut me off, and just try to act very defensive when I feel a bit tight.
Do I like it? NO! Do I keep doing it, NO! But it's a decision you have to make by trying it for yourself and learning about your rig and it's ability to stop in an emergency.
It's not the uphill section that will bother you, nor the flat down the road, it's the decision to stop and how well the rig handles that that will determine whether you go for it or don't.