The footage of the first phase got corrupted but the second and third phases should be more than enough proof that Veytharion Tier 3 Tessie-less isn't just doable but optimal. Which is weird given how much the map teaches you to rely on Tessie beforehand, it's like the opposite day of game design.
I didn't go down a single time, though there were some close calls during the fight. I also missed that I needed to be closer to Veytharion to recover my gauntlet ammo. Final time according to footage (including the corrupted stuff) was 7:57. Again, thanks to u/NeglectGod for prompting me to do this and I hope it proves to any doubters that his strat is optimal.