We made a sign with our company name and DOT number and put Not for Hire below it.
We plan to log and still have our own prepass.
Yes, Landstar.
I have never been clear about the use of "Not For Hire" signs on the truck when moving the truck for various reasons. There are many opinions offered by drivers, but finding anything official about this is difficult.
Your inquiry prompted me to look again and the only reference I find to "Not For Hire" in the FMCSA regs is in conjunction with the definition of a private carrier. It says there that if you are a private interstate Not For Hire carrier, you do not need to obtain operating authority.
They are talking about companies that haul stuff for themselves and not for customers who pay a common carrier to haul freight; like a hospital bed company that runs trucks solely to deliver and retrieve the beds it leases to hospitals, or maybe an auto parts manufacturer that hauls parts to plants and returns with empty racks. These trucks are subject to logging and other FMCSA requirements. The private carrier, not-for-hire distinction simply means that the companies that run such trucks do not need to obtain operating authority.
Your proposed solution is as good as any I can think of but you may want to check with Landstar for any guidance they may have to offer on this.
You will likely terminate your personal PrePass account when you find out in orientation that you can get PrePass at a lower fee through Landstar. It is also beneficial to have a Landstar registered PrePass transponder in your truck. Because Landstar has better SMS scores, you will get green-lighted more often than when you were at FedEx (Diane and I have been with Landstar five months now had have yet to be pulled in or pulled over for an inspection).
If your present PrePass transponder is still registered with FedEx, I would not use it going to Rockford. It may send a confusing signal to the scale house and attract attention. On a scale drive through, they will see a FedEx truck on the transponder but a DOT number that does not match.
This trip is as personal-use as it can get but you are also in limbo between two carriers.
When Diane and I once moved our new truck before it was registered, we did so using dealer plates and paperwork our sales rep provided. There were no DOT numbers on the truck and that attracted the attention of one of the most loud and rude scale cops we ever had the displeasure of encountering. He tied into me in a terrible way until a Lieutenant who was present overheard this lout, called him off and sent us on our way.
Regarding the DOT numbers and company name you will place on your truck for this trip, research the rules to make sure your numbers are large enough and spaced far enough from other lettering to make your sign legal.
When we moved our truck to Landstar, we printed the sign on our printer, put it in a plastic document protector, and used clear tape on all four sides to attach it to the truck and seal it from rain.
You are not the first person to move a truck some distance to get to a new carrier's orientation and signed on with them. I'd be interested to learn what guidance other companies provide. I don't know what Landstar says on this matter because we never asked the question (duh!).