I'll say my guys get the 94 cent roller covers, pop to the top off of the 5 gallon bucket, and shove it in using the wire drop in tray to knock
some paint off the roller, then spread the excess paint around the pole. It's like watching a 3yr old finger paint. The damned thing is, it always looks great afterwards. Compared to rustoleum, it's night and day. Usually rustoleum would look like a shiney, goopy pile of nap because it's so thick it seems to rip about half the roller off. Yes they are cheap rollers, yes I could get superior ones, but between the need to go flat on the majority of my polecovers/poles and the superior cleanup of the latex acrylic, I'll stick with the latex. Plus it stores for longer than the rustoleum.
DTM is a must if you're painting metal. Last thing you want is a shell of paint covering a nice solid piece of rust.
This is what I was thinking. They do work great if you're painting a new piece of pipe. We got heavy duty casters and welded them to 6" c channel. I'll have to look into your pipe roller...