I don't cock pump in public. I've yet to find a way to do it comfortably. However, in summertime I wear baggy gym shorts quite often and do full package pumping in a 3.5" wide mason jar. The way I'm built it's actually easy to conceal this way. Stuff it all in, suck the air out and it drops down perfectly at an angle where it doesn't really show much unless you're REALLY looking. I've even done this with my wife around to see if she notices it and hasn't said anything. And she likely would if she noticed. I've gone out to walk the dog with the jar on. As well as gone and got food at some local restaurants with it on while I waited in the drive through. Nothing out in the open though. I honestly feel I get a better pump moving around with a the jar pump on, likely due to the increased blood flow during movement I'd assume. So if I'm going to pump and have to do things, chores, etc. that's usually the route I go. Until I'm done doing things, then I switch out and do cock only.
Only time I think I've noticed someone noticing me was actually recently about 2 weeks ago. I had just taken it off after doing some chores around the apartment and took the dog for a walk. I was deep into my pump routine so I was pretty hefty that day too, It was around 7:30 PM, warm, sticky evening here in Texas. Naturally I was commando. One of the neighbors in my apartment complex who is an attractive younger female did a double take, she had dropped her keys as I was walking by and the wind printed my junk in my gym shorts and I caught her eyes quite noticeably linger. She waves to me every time she sees me now.

My wife asks me why she waves to me, I said, "I don't know, she must just be friendly." I'm pretty sure I know why though.