Many years ago I saw another cop wearing his IWB between his belt and pants. Initially I thought that was dumb. Then one day noting sweat and discomfort I figured I’d try it. Well I’ve been wearing my Glock 43 in a modified crossdraw appendix ever since. Super comfortable conceals well under a T-shirt.

My EDC when not working.

 

Which holster is that? Thanks.

 

I carry a G33 outfitted identically to my 43 for cold weather carry.

G33 w/TLR-6 DSG Arms IWB holster.

 

Alabama Hooker, no not that one, the 2nd one.... with Safariland 123 horizontal mag pouch

 

When I was doing appendix, I found 3 things that helped:
1. Adjust the ride height (depth) of the holster. Many are designed for super deep concealment and aren't comfortable sticking way down past the belt, if doing appendix.
2. Trim and smooth superfluous bits and sharp edges. Kydex can be uncomfortable and abrasive, but can be tamed with some sanding and trimming.
3. If a particular area of the holster is rubbing you the wrong way, you can add some padding. Double sided tape and felt\foam\leather can be applied to add comfort to sharp angles or edges.
Good luck