I don't know your exact circumstances, so my response may not be practical as it applies to you. But, it isn't very burdensome or difficult to carry one in a mag pouch on your belt or slide it in your back pocket (as I said before) or any pocket you choose.
No offense, but I don't think your #1 reason for not carrying a second mag is because you don't have anywhere to adequately carry it. There are TONS of adequate places you can carry a second mag; to name a few: on the belt, IWB, in any pocket, ankle holster, or inside a bag. Maybe you are sacrificing some comfort, bulk, or convenience, but location isn't the issue. But, I don't know your particular situation, so who knows.