Raise level of hearth well above floor and have it floating like this one
Q
Step in wall full width of room
Or just use extra wide has ambient fire raised off ground....spectacular at the end of your room.
Ignore style and color just look at shelf treatment left of fore and absence of capping
Simple and could work in your room
Continuous shelf as mantle ...but needs to be a higher version of this one
Raise level of hearth well above floor and have it floating like this one
Q