It's not clear why gravity needs to be "explained" in such a manner though. Nothing about our current theories of gravity requires the gravitational body to not be flat
One might attempt to banish magma, lava, and other indicators of fluid flow (the oceans, the atmosphere, planetary differentiation generally) and imagine an infinitely rigid lipped/walled plate underneath. However, then:
An eternally-accelerating flat plate does not generate the Weyl curvature tensor which a set of plumb bobs or zero-length springs can measure.
On the contrary the bulk behaviour of the source matter demands an ellipsoidal Earth: <https://en.wikipedia.org/wiki/Hydrostatic_equilibrium#Deriva...>.
One might attempt to banish magma, lava, and other indicators of fluid flow (the oceans, the atmosphere, planetary differentiation generally) and imagine an infinitely rigid lipped/walled plate underneath. However, then:
An eternally-accelerating flat plate does not generate the Weyl curvature tensor which a set of plumb bobs or zero-length springs can measure.
Even before General Relativity, such measurements were undertaken and characterized as smooth functions of distance from the Equator less than sixty years after Newton e.g. <https://en.wikipedia.org/wiki/Clairaut%27s_theorem_(gravity)>.