from memory gravitational pull is based on the variation in mass...

from memory gravitational pull is based on the variation in mass between two objects and distance apart so you are on the right track
However You seem to be not including other relevant variables
Regarding proximate gravity , There is a correlation between mass and volume but it is not linear as atoms of different elements have different numbers of protons and neutrons affecting their mass (one variable) , and are in different energy states from solid through to gas which effects volume (second variable)
Just one of those variables throws out your theory , ie if the mass at the edges is higher per volume it will balance out the loss in proximate mass from being close to the edge.
Geologists use gravity meters to measure the Bouguer , as they realise anomalies exist as to hanging weights , it is the stretch in the string that is measured not if they are hanging vertical or not.
People have been falling off the side of earth for thousands of years , but authorities will not publicly state the truth , many coffins have weights put in them instead of bodies to cover up the scam , cremation has made it easier to cover up what is happening .