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[MadMojoMonkey]

So according to General Relativity, all reference frames are equally as valid as one another.

I'm pretty sure you mean all inertial reference frames are equally valid.
Inertial reference frames (non-accelerating frames) are probably what you mean. If not, just say so.

GR can handle accelerating frames just fine, too, but that wont really help us in the case of photons or any massless particles.

However, let's look at this from the FoR of a photon. It gets there in zero time, and travels zero distance. Also a valid observation. The implication of this is that, from the photon's pov, the sun and the Earth occupy the same region of spacetime.

I just had a conversation about this last night that ran until 2:30 in the morning.

My issue is trying to visualize how it is that a photon which does not experience time can be a wave in the E-M fields.
My issue is visualizing how the 2D planar timeless universe of a photon can stretch out into a regular wave pulse that travels through 4d spacetime.

How is this not a violation of physics? How does the photon not observe a much denser object that is a black hole? How can two objects occupy the same location in spacetime from one FoR, but not another?

The short answer is
A reference frame moving at c is neither an inertial reference frame, nor is it an accelerating reference frame.
The equations we're using to try to understand it do not actually tell us about that special case.

It is a special case that we can only interpret the nature of through the use of mathematical limits. There are infinities in there, and we can't say what happens at c. We can only say the limit as something approaches c.
This is problematic because no object with mass can cross from less than c to c, and no object without mass can cross from c to less than c.

When we take the limit as v -> c, we are implicitly assuming that any object with mass will behave the same if it reaches c, but that's a false assumption. All we can really say is what happens as the difference between v and c becomes very small to an outside observer.
The speed of light is c in all inertial reference frames. No matter how fast you're going relative to another reference frame, light still moves at c according to you. So the idea that you've gotten closer to moving at c is bad language. No matter what you do, light moves at c in your reference frame.
The statement "as you approach c" is problematic. In your reference frame, you're not approaching c. The speed of light is unchanging, so you're not approaching it.