A path well-trod . . ?

Now I've started some serious reading in parallel with undergrad study, it is a relief to find that Gunnar Nordstrom came this way back in 1914.  With the big 5th dimension, out popped gravity, and it even unified with electromagnetism.  His work is being continued today.  It seems that it stands up well against Einstein's GR except (among other things) the prediction of light being bent around masses.  There are only a couple of bits of independent recent work on the web, neither refereed or developed, which also involve rotation. Just as Einstein was stopped in his search for GU by difficult maths, so it is probably the maths that defeats most people's progress.
What Einstein achieved was a solution for a number of key observations which makes it best, nay the only, viable theory.  To me in my naivity it looks like his maths has succeeded in flattening the universe into 3sd+t.  Those who understand it have no choice but to pursue it, and the rest of us can go and puzzle and dream.  Many attempts have been made to explain GR to the layman, including by Einstein himself and Eddington.
Although GR purports to be dynamic, I have not found it involving a rotation, and neither (I believe) did Nordstrom.  And GR is still 'king', even though dark energy and dark matter are known only through their gravitational effects, yet our best theory of gravity does not explain them.
Back to my own experience, I am aware of gravity not through skydiving etc but the mundane activity of barrowing piles of earth from A to B, every Thursday.  Now I know that if I lie on a fast-turning roundabout with my feet braced against a panel on the circumference, I will be restrained from being flung off it by a force through the soles of my feet.  And if I try to move a mass by my feet towards my head it will require work to do so.  If I look at the sky I realise I am being whirled.  And that force is no different from pulling down on me and the rocks as I go about my earth-moving activities.  Except that gravity is being focussed through the mass of the Earth.  The Earth, me and my rocks are all being whirled in space, causing it to be dented, and our sharing of the Earth's large dent causes us to be attracted together.  Simple.
There are some fundamental effects or values that the rotational 4sd+t model will predict, including dark energy, dark matter, and an absolute value for gravitational potential energy at infinity (which nonsensically is presently taken as 0).  This value will set a finite maximum on the gravity inside black holes, presently taken to be infinite at the singularity.  Why do physicists cling on to the idea that infinity is a real value, when it is obvious it is just a mathematical construct?  Finite gravity links with a finite radius of a black hole, within the Schwatzchild radius, helping to explain how its mass is somehow retained despite being "crushed into nothing".  Funny how the most efficient conversion of mass into energy occurs in the accretion disc aound a black hole (about 10% efficient), yet it does not in the even more extreme conditions inside the horizon.
My main realistic expectation is not that this model will survive scrutiny, but that it offers an "as if" explanation to the layman of how gravity works.
Mass couples to the 'medium' of spacetime just as electromagnetic charges, poles and waves couple to spacetime.  They have permittivity and permeability constants, mass will have a prehensibility constant.  It should not be too difficult to identify or find it.  But the model does require that extra big dimension.