I've been washing/polishing/sealing class 8 vehicles since 1985. I did the FreightShaker a couple weeks ago and the T-2 a week or so before that.
I use 5 gallon rolling mop buckets mop buckets, $40 8-16' fiberglass extension pole (I have one that's 23' for use on long aero models such as the 2002 T 2000 in my photo which was posted on the what you did detailing today thread), bi-level split bristle truck wash brushes, Bug Blocks, semi-circular stack brushes.
I've been doing it so long that I eyeball measure my pour into the bucket...depending on the severity of the grime. But no more than 8-10 oz per bucket. I also have a bucket that I mix 25 % (no soap) just for troubled areas such as the back wall of the sleeper, side fender-skirts, frames, and cat walks which pick up most of the nasty if there was an injector leak or such.
I also use the wash and wax that I pm'ed you. If you mix the degreaser too strongly, then it will affect the "shine" ingredient of the wash-n-wax.
Lastly, if you're planning on using wash mitts, you're gonna get soaked because much of your work is overhead and will run down your arms.
Do yourself a favor and go to youtube to view modern class 8 wash videos. Go by any Blue Beacon Truck wash to get an idea of what you're up against.
EDIT: I checked my AGO photo gallery. T-2 uploaded Sept 29. FreightShaker Oct 13.
Just get a gallon of wash and wax OTC for now. Mix it strongly, several oz per bucket, or use a foam cannon. Keep the vehicle wet and do not let the soap dry on the paint.