The road test itself is easy. Just take your time on turns and take them a bit wider than you think you need if your not used to a big truck. They turn well for a vehicle of their size. Take the time to dial in your mirrors/seat before you take off.
I drive an 18 speed at my other job and 5 speed was a little weird at first with the gears so close together but you'll get the feel for it halfway through. You're going to grind some gears but stay calm. If you accidentally go from 2nd to 5th don't panic, just calmly pull it out and get it in 3rd. They expect to see you're competent with the stick in traffic not perfect. Some people panic and end up having to stop right if traffic which wouldn't be good.
When they have you start on a hill from a complete stop, slowly engage the clutch with the handbrake still on and when you feel it grab pop the brake off, rev and go. Or if you're confident do the same thing with your foot on the brake.
If you know how to run a stick I wouldn't waste your money renting a uhaul. That's just me. Those things don't turn as well or have the visibility of a pkg car.
Good luck.