HI
I have 4 Jawfishes in a 110 gal. They all dig their burrows in the same corner of the tank, about 5 inches between them. Since I got them about a year ago I think they have not seen the other side of the tank, their radius is max. 8 inches around their hole.
The also ignored the area with the really high sand and went for a spot underneath a rock, the sandbed was max 3" deep in that area. Now at least one pair has formed, they were breeding several times now, but the eggs vanish after a few days. The most important thing is to prevent them from jumping out and to keep them with calm tankmates. In my tank they are the biggest fishes, the other tankmates are 8 Chromis, 5 Assessor, 2 Cardinals, one Blenni and one juvenile Scopas tang.
Because they do not move far away from their burrow it is important to make sure they get enough food. If the other ones eat it all before it gets to the Jawfishes, they will eventually starve. I feed tons of food (according to some other people my fishes may be in danger of becoming obese), so this is not an issue in my tank, but keep this in mind.
Best wishes
Jens