Hey
@tweakedonmeth 
Welcome to the forums dude. I hope to see more of you in the future. I can't believe the handle "tweakedonmeth" wasn't already taken. You really leave nothing to the imagination
So yea, what you're describing is possible and is pretty easy to boot. It sounds like you're already educated on the key points of this. Hopefully we can fill in the blanks for you.
Oxycodone/APAP (Percocet) can be separated using the Cold Water Extraction (CWE) process.
Like you have implied in your post, this isn't a "laboratory-grade" chemical process, so you will never end up with a ~100% pure end product. However, the process if very efficient, so the levels of binders/filler shouldn't be super significant. As described, if you were to take your post-CWE Oxycodone solution and let it evaporate, you'll be left with something pretty damn close to "pure" Oxycodone powder. I've always found the quickest/easiest means of facilitating evaporation is by pouring the solution into like a baking sheet (with edges, obviously) and sticking it in the oven on low heat. What really speeds the process along is having more surface area for the solution to occupy, though the heat also helps.
After that, the process of making a nasal spray is wicked easy. You can either put your CWE Oxycodone solution directly into the spray bottle or you can do the evaporation process. The primary difference is going to be the potency of your solution. If you want a potent solution, evaporation would be a good idea.
Make sure your solution is somewhat salty. The recipe for saline is 1tsp salt/8fl oz water. I'm sure it doesn't seem like a big deal. Saline is going to cause less irritation than tap water, which will keep your sinuses healthy for longer. Take you saline, fill your sprayer 90% of the way with saline, then add your powder and shake vigorously. The solution will likely remain stable on its own, though it doesn't hurt to give it a shake prior to each use to be certain your solution is homogenous.
Keep track of the total amount of Oxycodone you are using for the CWE process. Also take note of the capacity of your spray bottle. Furthermore, the bottle should indicate how much is discharged with each actuation of the sprayer. If you can't figure this one out, you can also just fill the thing up and count how many sprays you can do before the container is empty.
For example:
You have a Flonase sprayer or what have you. We will say this container has a 20ml volume.
You CWE 200mg Oxycodone from your pills, evaporate the solution as we discussed.
Fill the bottle as described above. Let's say the bottle you have can give 50 sprays before empty.
You now have a spray bottle that will administer ~4mg Oxycodone with each spray. I'm guessing this dosage and relative potency would be a good place to start. Let me know if you have any other questions.