This aestetic hook should bear quite some loads. It consists of a dovetail mount piece which can be screwed into the wall using a DIN 9135, DIN97 or similar screw. The hook is then inserted from the top onto the dovetail and locks into place.

The wall piece needs to be mounted with the smaller section facing the wall.

The Hook is roughly 40mm off the wall and has a height of around 20mm.

As per design I would assume the hook fails under heavy load on the Dovetail end, prior to any issues related to infill, so I think anything from 15 to 30% infill is fine.

The Hook gets more sturdy especially when using more than two wall loops. The dovetail end of the hook and the wall mount will be a solid part when using 4 or more wall loops, which I recommend.

As for supports, I have printed the hook upright and put support material underneath it, as this is usually not visible and gives a better finish, espcially inside the Dovetail. 
I use OrcaSlicer and defined the Supports manually, like so:

You could also roll it over and support the Dovetail, but this might impact the wallpiece sliding in easily.

Enjoy and happy printing!