zone 6.5 NJ.

in the hellstrip aka boulevard aka right of way, i.e the strip of grass between the sidewalk and street, there was a 20' Maple about 8" diameter the city cut down. Wasn't even declining the owner said. I told owner to call the town and they might replace it free since it's their property and tree and shade commission etc sometimes will gladly replace it. Same thing happened 3 houses down and I had them call town and they did replace the tree but this one said they wouldn't help out.

Since I can only remove the roots in the grass strip and not the ones under the sidewalk or possibly under the street if there is any, how risky is it even if the tree is kept on a drip line that it will just die in a few years from lack of rooting space? Wants to install a $125 6' maple to start with so it fits in decently. Should I remove as much of the old stump that I can and space the new tree at least like 4 feet over? That'll look a bit odd and almost be on the neighbors side but I think anything that increases the chance of survival is worth it to not waste the time effort and money to water and plant it too close to the old root (I'll remove what I can but obviously can't get under sidewalk and am not going to rip up lawn looking for old roots as none are visible on the surface).

I don't recommend maples for this location as they get huge and once start buckling sidewalk usually gets chopped down but they are persistent to install a maple here. The whole block has maples that are only about 15ft tall and been there for decades, not sure if they're kept pruned but I would assume no maple grows that short and slow but would like recommendation for slow/small maple that's least likely to buckle sidewalk and end up just being removed sooner than later.