First, you wanna make sure you're pushed up against the wall of U-haul like I am, then make sure you're placing the wall from the second step down from the top of the stairs. Then rotate it like I did and make the jump. Make sure you quickly run outside of U-haul on top of the wall before it completely fortifies though, because if you don't then you're gonna be trapped in U-haul or break the wall from hitting your head on the curved roof. Also make sure you don't over-rotate the wall, because then it doesn't make the extra block of the wall connected to the truck (and it also just makes the jump a lot less narrow).

https://reddit.com/link/lvfiut/video/fe22nmzrfgk61/player