The Thorough Crusade challenge seems a bit too overtuned for the tech adept. Certainly for a tier 3 challenge it is a massive hurdle for the TA, it would appear. Even the tier 5 Legendary Crusade would be easier than beating the 60m timer with a slow, methodical class (with very underwhelming AI minions) like the TA.
I've decided to give it a try, but am nowhere near the objective. Granted, I am not yet at max level and my build is not fully optimised. However, I do have mostly ancient relic / archeotech gear with three doctrines slotted in and destruction amplification active. I also got the astartes summon from Rebus for this VC attempt.
Now I'm at 45 minutes of my Ebony VC attempt (seems to be the fastest VC to do this challenge) and with some 5 missions remaining, all +7-8 and more at this point.
I can perfectly see doing this on my psyker main. But with TA, it just doesn't look realistic at all...
Edit: just to add that I obviously ignore as much of the regular mobs and bosses as possible, rush to the objectives and teleport out as soon as the mission complete pop up appears - no unnecessary detours or fighting.