My safe was set up somewhat similar to yours.
Looking at your safe I found the left side (rifles in formation) to be useless. You cant possibly fit the number of rifles in there that the slots would suggest.
To compound problems I like to kepp my rifles in the safe butt stock up so I compound my space issues.
Im guessing that on the right side of your safe if you remove the shelving the top is a "U" that has slots cut for rifles.
That "U" formation I found to be best for me to store rifles "butt up, bore down" so I built a new top shelf with two "U" storage options instead of that rifles in a "Formation of Ranks" option.
When I cut the slots in my "U" I staggered them so the rifles were not opposite each other but staggered.
When I set them in the box one rifle goes in on the left, the next is on the right, etc.
A local upholsterer used some fabric to cover my new cut plywood storage design.
Its worked better. You dont have bulky action next to bulky action so the rifle arent really banging each other, still though, you find out quick not many rifles will fit in the safe and the guys that write the capacity in sales brochures are bald face liars.
Many will recommend safe rods. They would probably allow you to maximize space but they wont work with my "bore down, oil leaks away from the action" desire.