Can Iron Man infiltrate the Ultramarines? (Marvel/40K)

For reasons important to the survival of the multi-verse, Tony Stark, with the assistance of Dr Strange, has to hop through time and space into the 40K universe and infiltrate their most famous Space Marine chapter for a couple of weeks without getting caught or killed.

Thanks to Strange, Tony has a reasonably solid understanding of how the Imperium and the Space Marines operate, and he has six months of prep time to build whatever he needs at Avengers Tower.

When the mission begins, Tony is dropped via portal onto a secluded region of the planet Macragge, the Ultramarines' home base, along with everything that he acquired and created during his prep time.

Is this mission doable for the smartest Avenger, or is it doomed from the beginning?