Roll cage install with a question

Visually, it would help if it was snugged closer to the inner door and headliner.

Is it being mounted to the floor with plate? Might be worth the re-do and 'shelf' you refer to.

Still, you made one at home. Not the easiest job.
NHRA wants 6"x6" plates I believe. Saw something somewhere in the NHRA book that no grinding on the welds allowed....I think