I’ve had two mark 6 transits, neither had that much of a problem with the barn doors unless the wind was really strong (we would close them on the hose at that point anyway, you can close them in a way that the doors weren’t fully closed on the hose but the catch caught on the other door therefore holding in place)
Rust on the first one on the other hand was a pain in the harris, second one was in great condition and waxyoiled as a result (I miss my second one, best van I’ve had, regret selling it)