Not all of it is super overpowered, most TO skill use or things like the ranger who can shoot in 10 mile range increments (but cant spot people at that range) are not what I would call overpowered.
Spot rules are pretty dumb sometimes. I haven't done the math, but I'm willing to bet the -1 per 10 feet rule makes the sun effectively invisible, even with however much of that is negated by its size categories.
Decided to do the math on a whim.
I assume the distance of the campaign world to the sun to be 1AU, or approximately 1.5x10^11 m, or a bit under 5x10^11 feet, resulting in a penalty of about -5x10^10 to see the sun. In any given campaign setting, the sun might be closer (or farther away), but given that this is the only measure we have, it's the only useful assumption.
The average diameter of the sun is about 1.4x10^9 m, or just under 4.6x10^9 feet. If we consider Fine to be size category 0, then the formula for an object or creature's maximum size in a given size category is 0.5*2^n, where n is the size category. So the size category of the sun is log
2(2*4.6x10^9ft), rounded up, or 34. That puts us a total of 30 size categories above Medium, so extrapolating the progression of k*4, where k is the amount of size categories above Medium, we get a Hide penalty of -120.
So, yeah. Good luck making up that difference, even if we assume being a giant ball of plasma gives you a further penalty.