Suggestions on optics/BUS mounting

Getting ready to put my AR AR pistol together. With a 7.5" barrel, there's not a lot of room on the top.

If you mounted back up iron sights would you go behind or in front of reflex sites? I'm thinking behind (aft) of the sight. That would give a longer sight radius. What about 45 degree offsets?

For me it depends if you like to co witness your sight or not. I like having a clear range of vision in my sights so I would go more 45deg on my buis. Or may be run two red dots at once with one a 45 if i had money to run two of them.

Red dot mounted as far forward on the receiver as possible (not on the hand guard), rear sight to the back as far as possible, front sight as far forward as possible. This goes for all ARs I have ever set up regardless of barrel length.