Sonos Arc Placement

I am considering purchasing Sonos speakers and considering a variety of approaches. The room is about 12 X 20 X 9. Our sitting area is about 8-10 feet from the TV. The TV is a 3 year old 55” Samsung, it has ARC HDMI output but not eARC. We have a new Xfinity cable box and good Internet connection.

The TV is currently mounted above an enclosed gas fireplace, which has an 8” shelf on the top of it. The TV is mounted to the wall above the fireplace shelf on a swivel arm connected to the wall which lets me move it out to be flush with the outer edge of the fireplace shelf or all the way back to the wall taking up ~2” of the shelf.

The swivel does not let me raise or lower the TV at this point.

I like the idea of a Sonos Arc (and optionally 2 sonos one’s for rear speakers), but not sure if this will fit our setup.

I see two choices were we to get a Sonos Arc: 1) raise the height of the TV so that the Arc can be on the shelf above the fireplace - either by adjusting the TV swivel arm (i.e. re-attach it to the studs it is on now) to be 6” or so higher and fit a Sonos arc on the same shelf under and in front of the TV or by replacing the swivel arm entirely with legs that would raise the TV up and move it to the back of the shelf, or 2) put the Arc on the ground in front of the fireplace (out a bit so it doesn’t suffer heat from the fireplace).

Is having the Arc on the floor a bad practice?

Should I look to a different solution than a sound bar altogether?

Thanks!