In answer to the specific question: no, you shouldn't have to do the entire guitar (unless, of course, you jacked up some of the rest of it in the process of working on the top).
You don't say - and I don't know older models enough to know - if it has binding around the top, or uses the maple-showing faux-binding trick. In either case, if you just mask obsessively carefully around the perimeter of the area you want to have your way with, then enclose the rest of the guitar in something protective the whole time you're working on the top, you should be fine.
When I've patched in finish areas, I've used the kind of softish foam bags computer monitors - and some guitars - sometimes come bagged in. And if I think I'm likely to bang the thing around while working on it, I'll pad inside the bag as well. (As a possibly helpful aside, I recently accidentally discovered that a big - and tall enough - box full of packing peanuts makes an ideal work "bench." You can cut a scoop in one side to hold the neck, and - if the box is the right size - a similar scoop in the other side to hold the body. But when you need to work on all angles, you can shove the guitar down into the packing peanuts to get it at exactly the right angle for your work. Maybe not needed so much if you're only working on the top, and maybe you already have a well-protected and guitar-securing work surface, but this discovery came in handy when I had to work all around a headstock or a guitar rim.)
Anyway. As long as you keep the whole rest of the guitar taped off and protected - and have the buffer zone of binding or faux-binding to segregate the two areas of the guitar (ie, the one to be worked and the rest of it) - you ought to be able to proceed with impunity on the top. Think of the way surgeons drape a body for access only to their work area. That would be the idea.
Having never stripped a Core PRS (and only accidentally exposed bare wood on an SE), I won't weigh in on whether to use heat, chemicals (and which ones), or just sandpaper, and of course I can't speak to your inherent skills with any of those. If I was going to approach the project and I was worried about balling it up (as I would be), I'd find out exactly what finish is on the guitar now, get some and slather it on some scrapwood of similar species, and try the various removal protocols to decide on one and perfect my technique.
I have no doubt whatever that you can get through the clearcoat and down into the dye layer on the maple. But of course I can't promise you won't distort the contours if you get carried away, and I can't speak to how completely you'll be able to disappear any dye. The thread linked above is highly educational on those subjects, and also illustrates that the job itself may teach you how it can best be done - nother words, you may have one outcome in your mind's eye, and then be able to adjust that vision based on how the stripping and sanding go.
Like can you get it to 100% white, unstained maple - and how much material would you have to remove to get there? Don't know! And how much would it matter, either tonally or cosmetically, if you had to go deep to get to untouched wood? Don't know that either! Like the feller in the thread, you may be left with ghostly shades of shades past, and need to come up with a color strategy to incorporate them. I do know that it can be devilishly hard with bare wood (and even matte-sanded color coats) to see whether you're creating dips and scoops in otherwise flat and/or gracefully contoured edges as you sand. But every done-it-myself-by-hand imperfection will show up nicely once you bring it back to a gloss coat. So be cognizant and ever vigilant.
But whatever happens to the top, the rest of the guitar can be made safe from your predations. (This assumes you're going to work on the job promptly and steadily till it's done; I can't promise what will happen if you bag the rest of the guitar in some impenetrable plastic barrier and it goes through multiple freeze-thaw cycles or is stored in a rain forest (or the midwest) through a humid summer).
In some ways - as long as you have the cojones, desperate intention, and/or skill to commit to whatever it takes to finish the job once you undertake it - a top is easier on a PRS than the back, sides, and back of the neck, because they're often a unified color block and continuous finish block. Once you start on those surfaces, where do you stop? Also, I'd rather work on a top than sides and edges.
If you dive in, take pics. I'll be curious to see how it goes.
