This... You want the grip over your gut, not underneath it, for any semblance of comfort. Under the gut might hide better but it will impede the draw and rub/poke you raw.
I started AIWB carrying a G19 at 5'7", 190lbs and made it work. A proper holster (RCS Eidolon at that time), a rash guard (Under Armour Heat Gear), and sticking with it until my body adjusted to the sensation, was all it required. Plus a lot of tinkering with holster set-up and position and using a proper AIWB belt to maximize concealment and comfort.
I have since dedicated myself to improving my body and am now 163lbs, however I have been less successful with increasing my height. I still have a slight pooch in front but it's a non-issue in regards to comfort or concealment.
After about a year of exploration and experiment I am now carrying a Roland Special in a Henry Holster Spark and find this dummy big combination to be equally as comfortable but more secure and concealed than anything previous.