[Tifosi]

Has appendix carry been considered or tried?

Provided one can get a holster at the proper angle based on your physique its pretty comfortable in general with a couple exceptions like seat belts and you can bend over without creating a super print on your lower back.
Secondary advantage: pistol can be drawn with either hand, even while seated.

AFA shoulder holster, I would highly reccomend vertical carry over horizontal carry.
Unless you've got a really odd shaped handgun the length is always a larger dimension than the height and people tend to have a longer measurement from armpit to waist than they do the for to aft thickness of the body at the chest line.

EG: if you're around 5'8" or so and up, of average build and weigh around 135~140~ish and up you can vertical carry a full sized 1911 and make it dissapear under a basic unlined jean jacket or partially buttoned flannel shirt. Turn it horizontal and you end up with very obvious lumps on the torso on either side of the upper arm.

Not as floppy as horizontal carry either as a result of less leverage and more solid reinforcement due to significantly shorter holster to waist belt strap length

 

[Tifosi]

Appendix is roughly between twelve forty five and one o'clock
Or eleven and eleven fifteen if left handed or right handed desiring a cross draw

The actual organ is on the right. Or where the scar is if you've had it removed.