from your description it is not too dissimilar to my F350. My guess is the inner fender well needs to be removed to access the nuts.
this is how the strut mount attaches to my truck
2011 F350 6.7L Diesel 4x4 CrewCab longbed Dually, 2019 Lance 1062, Torqlift Talons, Fast Guns, upper and lower Stable Loads, Super Hitch, 48" Super Truss, Airlift loadlifter 5000 extreme airbags