If there is an overhang the following principles can legitimise what would otherwise be a trespass.
Roof to gutter overhang.
Since there is only about 3 4 of vertical material to anchor gutters clips are there any specialty hardware or other techniques to hang gutters along this facia.
The bottom tile or slate of the roof covering should project at least half way into the gutter the ideal distance is between half way and two thirds of the way over.
Home centers sell a gutter apron in 10 ft.
I have a roof that only has a sort of moulding that transitions from roofing to the walls.
If water is dripping behind your gutter it s probably because it was installed without any flashing over the back of the gutter.
If you can get or make brackets long enough yes screw them to the wall.
Hopefully the photo will illustrate the problem.
The deeds to the house may specifically provide a right for them to be there.
The gutter apron will prevent the dripping.
Metal is usually installed on rafters or strip sheathing rather than the solid decking used under other materials.
I have the same problem but in my case the roof sticks out 18 so i simply drilled small holes at the end of the roof and attached wire loops to hold the gutter in place.
If the overhanging gutters have been in place for over 20 years then the owner may have acquired a prescriptive right for them to be there.
You run a drip edge which has a 3 quarter to one inch edge on it over the gutter then mark on the panel each side 3quarters cut the mark you left with a edge the width of the pan three quarters long take your tongs or panel turner turn it under then slide the panel onto the drip edge thats hanging that 3quarters or inch over the gutter till the turned edge of the panel wraps around the edge of the drip and theres your overhang a nice uniform rounded end.
Gutters should be hung where a straight edge laying on your roof shingles can easily extend over the front lip of the gutter this is the proper installment location for the high point of the gutter.
The reason for this is that whenever rain runs down any type of roof when it gets to the lower edge it clings to the tile or slate by capilliary action this means that the water actually runs around the bottom edge and slightlly back up the rear of the tile before gravity allows it to drop into the gutter.
In almost every instance gutter installers take the path of least resistance and shove the gutter right underneath the roof shingles instead.