To the best of my knowledge, the issue is never directly addressed. The rules, on a quick scan, appear the same as in 3.5, where this issue has been debated some as well.
The long and short of the argument is this: the statement in shadow evocation et al. is that someone who knows that it is fake does not need to save. Nothing says he does not save or may not save, just that he doesn’t have to. This is taken to mean that this is optional, and effectively someone in this position has the option of automatically succeeding on his save the same way you typically have the option of failing any save. You may, according to this logic, choose not to automatically succeed, and then, since you are now attempting a saving throw, choose to automatically fail.
Strict-RAW, this seems most accurate, though it definitely takes a few steps to get there and it’s clearly not written out explicitly. Still, the language, whether it was intended to be or not, is precise: it waives a requirement to save, it does not add a requirement to not-save.
Whether or not you should rule this way in your game is more dubious. Shadow evocation et al. are rather useful, particularly for this feature. In 3.5, greater shadow evocation was typically used to cover the loss of contingency due to the banning of Evocation as a specialist wizard. In Pathfinder, this is less of an issue (since banning is no longer so absolute anyway). Most of the time, shadow evocation et al. are most useful when the drawbacks of using them (the Will save, the quasi-reality) don’t actually affect the functioning of the spell, which is precisely in this case: buffing. Ultimately, it becomes yet another powerful and flexible tool in the wizard’s toolbox, and he’s already got a ton of those. Shadow evocation et al. are’t the most powerful of them, but maybe it’s worthwhile to you to start paring down options where you can.
Yes
But those who interact with it are allowed a Will Save. So if you cast right in front of your allies, you can tell them that it's an illusion and they can touch it and gain a will save, those 50 feet away are not allowed a will save until they interact with the illusion in some way, such as shooting an arrow at it.
Silent Image is a figment:
Figment: A figment spell creates a false sensation. Those who perceive the figment perceive the same thing, not their own slightly different versions of the figment. It is not a personalized mental impression. Figments cannot make something seem to be something else. A figment that includes audible effects cannot duplicate intelligible speech unless the spell description specifically says it can. If intelligible speech is possible, it must be in a language you can speak. If you try to duplicate a language you cannot speak, the figment produces gibberish. Likewise, you cannot make a visual copy of something unless you know what it looks like (or copy another sense exactly unless you have experienced it).
Because figments and glamers are unreal, they cannot produce real effects the way that other types of illusions can. Figments and glamers cannot cause damage to objects or creatures, support weight, provide nutrition, or provide protection from the elements. Consequently, these spells are useful for confounding foes, but useless for attacking them directly.
Also, the spell says it does not create texture, so if they touch the wall with their bare hands, they will most likely automatically know it's not real (no will save required) and can walk right through the illusion, but will not see it as a translucent image unless they pass their save.
The illusion does not create sound, smell, texture, or temperature.
If someone (ie: the caster) tells them that it's an illusion, they gain a +4 bonus to their will saves:
If any viewer successfully disbelieves an illusion and communicates this fact to others, each such viewer gains a saving throw with a +4 bonus.
The thing is, if wether you know it's an illusion or not does not automatically make your brain believe it. That's the point of illusions, tricking the senses. Though i do agree that it's the magic school that sees the most table variation in the game. Even if you know it's a silent image, like identifying it as it's being cast, someone told you what it is and what it does, the image is there and looking very real to you. Knowing what the spell does will allow you to walk right through without analyzing it, but it does look like a real wall to your character.
What counts as interaction is normally up to your GM, as the rules do not clarify that, but that will depend on what is the illusion and how people could interact with a real version of that illusion. The Ultimate Intrigue defines this interaction as spending at least one move or standard action with the illusion, but whether or not your table uses that rule is the GM's decision.
What is interacting with a wall? Touching it, trying to climb it, hitting it with a hammer, shooting something at it, etc.
What is not interacting with a wall: Looking at it, talking to it, waving at it, yelling at it, etc. Note that some of those examples could work against other types of illusions, such as an illusory dog or bear, and would probably allow a will save, but not against an illusory wall.
Best Answer
Yes, because other illusions can do similar things
I am not sure if there is a printed spell which will do this, but I would say it is possible. My reasoning is that other spells can do similar things. What you want to do here is to allow vision through an object. Disguise self allows you to appear a foot shorter, so it must allow vision through your head if you do.