Yes, you will need collector plates for your truck...here are the details:

WA State Licensing: Collector vehicle plates

You just can not "borrow" a car with insurance to take your driving test. Since you only have a permit, you will need someone in the car with you who has at least five years of driving experience (in addition to having insurance on their car). You kinda will be borrowing the car at the time you are taking the test with the evaluator since the owner of the car has to sit it out and wait for you. Do not show up with someone's car without them being in the car with you...