UkranianTitan, I have almost the same stats as you length and girth-wise, though I am going for 6 inches in girth (5.4 midshaft currently). I am trying to do this all manually with dry jelqs and ulis, except for clamping. I use a thick soft rope for that, which I use to clamp off behind the balls. The reason why I use rope, and not a cable clamp, is because I need to be undercover too like you. I have been clamping for about 3 months, and I am seeing/feeling results (gained .2 in girth).
About pumping. I tried it but I was super paranoid about someone discovering it. Also, I think it really fucks up your dick. Sure, your dick is impressive after a session, but you over do it and you are out of commission for 3-4 days at least. And the shit is not permanent at all. It doesn’t make sense if you think about it. It pulls the outer layers of the penis and sucks in fluid (not blood). Your dick swells, but the corpus caverna does not get pumped out to the maximum, which is what you need for girth. When you clamp you can feel it and the results stay, I am pretty sure. Good luck with your quest for fatter dickdom.