I share a lot of the same sentiments as what JamesPaul said above.
Based on some advise from member GuitarDoc, I gave it a try with having the Bridge pup situated so that the Rail coil faces the bridge. I prefer the pup this way. I did also try it with the Rail coil facing the Neck, but I found - just like GuitarDoc advised - that the Rail coil gained more personality by facing the bridge. And it did not seem to have any impact on the P90 coil.
In my opinion, the Rail coils on these pups are not Stratty in character, but orienting it like I have it, it is working well at faking Telecaster style singlecoil tones. The Rail coil in both Neck and Bridge P-Rail pickups is a little weaker than I would like in terms of strength and output- and if you search threads in this forum about these pups, you'll see where others have said this, too. So when I do use the Rail coil, i actually use both together vs just one of them. And I did end up also orienting the Neck Prail so that its Rail coil is the outer coil instead of being an inner coil. I found that helps to achieve the Tele like sound I am going for when I use the Rail coils.
I actually just installed the Prails in a test bed guitar about a week ago, so I am still getting acquainted to these pups.
Another point you may find useful: if you decide to go with a set of P-Rail pups, I have found the combination of Neck and Bridge pups * wired in parallel * to be a very glassy, almost Stratty tone, on a clean channel. It's a really really good clean tone.
* CORRECTION: i originally wrote "both pups wired in parallel and then each split to the P90 coils" directly above, but the next day I went back and checked my settings on this guitar. It was actually both HBs wired in parallel, no coilsplits. On that basis, I've also removed the now non-applicable comments I made later in this reply about having each pup first wired in parallel before doing coilsplits and whether the Tripleshot rings could do that, yada yada.