It has been years since I wired romex in Pa. but I'm picturing a box with a pilot lamp and a 3-way. A 12-2 is coming from my feeder, a 12-2 to the load, and a 12-3 to the other 3-way. I would put black electrical tape on both ends of the white in the 12-3 and that would cover the pole and 2 travelers to the 2nd 3-way, which would come back to the 2 travelers of the 1st 3-way, and the black from the feeder. The pole from the first 3-way goes to the black to the load and the pilot hot. The feeder white and load white get pig-tailed to the pilot neutral and we're done. I guess you just have to figure out your box fill with the devices. Sounds like a deep box. Is that what you have in mind?