Circling back to this. I passed this time, my third time taking it, first time in transportation (first two times were in structural, yikes).
For the breadth portion, I did self-study each of the three times with some help from the CERM examples in the book, the accompanying Practice Problems and Solutions book you can buy, Civil Engineering Academy Practice Exams (https://civilengineeringacademy.com/breadth), and the official NCEES Practice Exam. In the morning, I exclusively used the CERM as my only reference. I had the 15th edition for all of my attempts, which was still plenty new enough to get the answers and have current information, as not much of the stuff in the CERM will change very often. Some of the problems in the CERM and the accompanying Practice Problems book can be a little too lengthy and contrived, but if you adhere to the list of topics covered in the breadth portion given by NCEES (https://ncees.org/wp-content/uploads/Civ-Str-April-2015_combined-with-codes-1.pdf), it will help you weed out some unnecessary chapters and examples. Even if the problems are too long, don't discount their relevance if they are within a topic mentioned on the spec sheet. Tab your CERM extremely well, by topic, not by chapter (e.g. Open-Channel Flow instead of just "Chapter 26 (or whatever it is)"). Depending on how many practice exams you have access to, I would save at least one for the week or 2 weeks leading up to the exam as a final review and a fresh look at new problems, which will become increasingly harder to come by.
I took the EET Transportation Depth On-Demand course (http://www.eetusa.com/classes/civil-pe/depth/transportation). YOU SHOULD ABSOLUTELY TAKE THIS COURSE!!!!! Samir, the main instructor, is an incredibly effective instructor and is great about answering any questions whether you're in the live online class chat or emailing him after watching an on-demand video. The classes take place on Saturdays (typically from 8am-5pm), and there are also 3-4 problem solving sessions (homework problem sets) throughout the course that have a mid-week solving session video. I felt the on-demand worked better for my schedule and actually allowed me to get ahead of where the current class was since I started studying earlier and had access to all of last cycle's videos right away. I committed 2-3 hours per night during the week and ~4 hours on Saturday watching videos either to stay caught up or to get ahead. The videos don't change by any huge measure, aside from any reference code changes (which looks like will just be the Green Book for this coming Spring 2020). As soon as you sign up and pay, you'll be sent a binder for the upcoming class. That binder is incredibly useful, extremely thorough, and should be tabbed thoroughly (more than what it already is) for easy access during the PM test. It has several practice problems at the end of each chapter as well as examples throughout the chapters. This course also comes with a simulation depth practice exam that's released about 3-4 weeks before the actual exam that will be uploaded to the course's website for download/printing. For other practice exams, I just used the NCEES Practice Exam and waited to take it until the week before the actual exam.
(As a side note, I have a friend who took the EET Breadth On-Demand course and had just as high praise of it as I have of the depth course. It also comes with a simulation breadth practice exam and has more instructors than the depth, but you get another separate binder entirely for the AM portion as well as tons of practice problems throughout the course. The same rule applies concerning receiving the binder as soon as you sign up and pay in addition to having access to the previous cycle's videos.)
As for references, get as many as you possibly can and make sure they are the correct edition, especially as it concerns the Green Book, HCM, and Roadside Design Guide, as those seemed to be 3 of the most utilized historically. With some strategic Googling/free trials of services, I was able to get almost all of the references in PDF format and print them off and bind them. Well worth the hassle, even if you don't use them all. Peace of mind is incredibly valuable, as you'll come to find out.
If you'd like clarification or further elaboration on anything, let me know! Best of luck to you all!