Hmm. I would like to add positive constructive criticism.

I like your tube choice- it's overkill, but that's a good thing.

Google "miata roll bar". That's a shrimpy little car that barely weighs anything, and they almost without exception have
1) cross bracing
2) forward/rear bracing.

Yes, that Dodge came from the factory with no bracing at all, just a picknick basket handle sticking up. LINK
 The cheapest solution the beancounters could squeak past DOT regs doesn't seem like something to copy, IMHO.
Check here for some much newer factory cage failures.
https://irate4x4.com/threads/roll-cage-failures.50590/

I think those bushings look like a terrible idea. In fact, they look just like this gate hinge:


I understand the isolation benefit, but the other side of that is that your "cage" is now a free-floating structure, and gets no reinforcement from the frame. Those tabs and bolts won't add up to anything in a wreck. The cage needs to be rigidly anchored to the frame, and the seats need to be suspended from the cage, creating a lifepod. The sheetmetal body is disposable wrapping paper.

Needs more triangles! Squares turn into parallelograms. That big upside-down 'U' can crush sideways, and pivot forward and back on it's hinges. Imagine you blow a tire on the highway, catch a ditch, and are sliding down the road on the rollbar at 55mph. What keeps that bar from flopping back into the bed?

At minimum, it needs a diagonal crossbar left to right, and door bars next to the seats, triangulating forward to the frame.

A couple more links:
https://irate4x4.com/threads/minimal...designs.46225/
https://www.pirate4x4.com/threads/no...1067505/page-2

I get that you're not racing or rockclimbing, but highway speeds with kids are no joke either.

For serious no-nonsense engineering advice, you might post up on https://irate4x4.com/. It's got Ultra4 racers, pro fabricators, and a bunch of obnoxious trolls who know their stuff.

Anyway...there's my opinion!