Here is what I used to paint my roll bar. It goes on with foam brush. I painted mine in the truck. I did not bolt it down, this let me move it a couple inches to get the best angle on it. It is tricky and takes ALOT of patience. I put a tarp down for the main stuff, once it was dry, I pulled the tarp and put down some paper to do the edges of the flat steel. IF you can take the topper off, that makes a big diff. I did not take my topper off. How you see it, is how i painted it.
I would strongly suggest NOT spray bombing it, if your circumstances were like mine (topper on and cage installed). Youll get overspray everywhere. If I had pulled the cage I may or may not have spray bombed it. I like the brush on stuff, it worked well. Less mess and overspray IMO.
With the pint can, I could do a couple cages Id imagine. I put two thick coats on and barely put a dent in the usage of the paint.