OP asked about firearm choice. A G19 with a gadget, a P2000SK, depending on how baggy your pants are in front, or even a P2000 could work. G19 sized 9mms or smaller work well with a Smartcarry. An advantage to the P2000sk or P2000 would be a longer trigger-pull in a place where trigger is not protected by a hard holster.
If double stack is too fat, you could do a Wather PPS, Glock 43, or Kahr single stack of some type.
Then again, one could always go J-frame...