I carry my Shield 9mm loaded with the 7rd flush fit magazine IWB in a Galco King Tuk hybrid holster. I further carry two 8rd extended-fit magazines in front slash pockets. Basically in 2012 and some '13 and '14, I invested in about 11? pairs of LA Police Gear pants (a few different sub-styles of their Operator line) and 4? pairs of their shorts. These are all amazing, amazing clothing that count as pieces of kit. Some of them 8 pockets, some 10, 11, and even 12. They all have two hands-pockets, two rear hip-pockets (where you'd put your wallets etc.) two cargo pockets, and two front 'slash' pockets between your hand-pockets and fly, which are custom made to hold pistol-mags. And these pockets are also on the shorts.
Since I got to FL, I basically have been wearing shorts every single day. I wear each of the 4 LA Police Gear shorts and then usually 2 more days other cargo-style shorts, sometimes more. Back home in Jersey it's pants-weather a lot more than here so I wear those pants (But of course couldn't carry a gun lol). So fortunately i always have room for spare mags.
In my setup, I have a loaded Shield with 8 rounds of 9mm plus two more loaded 8rd mags, which gives me 24 rounds of high-quality 9mm (at the moment, Winchester 147gr Black Talons). I know it's not the same as having 15+1 Glock 23 in .40 S&W with 2 15-rd spares but, I realize CCW/EDC is not preparing for war or working a duty shift. I might try to buy some more 8rd mags for the Shield but I wouldn't be carrying more than 2 very often if ever.
I like how you think.