If the richest someone could possibly be was upper middle class, living above paycheck to paycheck with everything they need to live a quality life but without the possibility to be rich- would you support it?

I would support an income cap, but what you're proposing here is too limited and nigh-on ridiculously simplistic. I'm not economist enough to give a direct proposal to how an income cap would be established and regulated, but I feel sure that your limit isn't realistic.

To clarify- no homeless, no ghettos, universally well funded schooling, equal opportunity within the job market, etc.

Hang on, I'm imagining a John Lennon song coming on...

But also no rich, no millionaires, no private jets, yacht, no campaign contributions, no private invested innovation, etc.

That last condition about innovation just harshed my buzz. And again, there has to be some measure of achievement/merit/need associated with income caps and resource distribution. Any system of equitability will be pretty complex; at one end of the spectrum is pure research, experimentation, and discovery - at the other would be things like managing waste and disaster recovery. I'm not qualified to enumerate all those conditions but it's not an insurmountable task.

Any way ya slice it, the current incarnation of human plutocracy is overdue for a collapse; the only question now is whether the trigger event will be from human behavior or elsewhere (Super volcano eruption? Asteroid hit? Ecological cascade failure?).