Unless you're super skinny trying to conceal a full size pistol a good IWB holster won't print enough for the usual person to notice. Guys I've worked with for years at my shop didn't know I carry every IWB day and my T-shirts aren't even baggy. When I ride I use a Verscarry OWB for my Sig P365. Under a flannel it disappears completely and doesn't dig into my side. I won't get off into the weeds about how much training time should be mandatory to draw fast from concealment, but fumbling with that bag thing to draw would be highly inefficient.