Undercoated our 17 using one gallon of Woolwax Black and the Keller PRO gun w/ wands PRO Gun and Woolwax Black. That is one of those jobs where I can see why people pay to have it done, and why businesses charge a fair amount to do it. It's a messy job, and you will be sore from being under the truck for a while. Total job from pressure washing to having it back on the all four wheels was probably 12 hours. I accomplished the entire process with a small pancake compressor. Yeah I big compressor would have saved a bit of time, but because I used the wands the majority of the time there wasn't a big CFM draw.

1) Pressure washed with foam cannon and dawn dish soap, and let dry for a week.
2) Put GX on jack stands, but remove the spare first.
3) Remove wheels
4) Remove all skid plates including the one for the KDSS module, as that one gathers a ton of road debris, and I wouldn't coat the back side for fear of it gathering even more.
5) Cover brake rotors and calipers
6) Cover garage floor with disposable drop clothes, spread them out tight, and tape them to to the floor. I wouldn't use the super thin ones because rolling a creeper around on them is a royal pita, and I wouldn't suggest sliding around on your back due to the amount of WW that lands on the floor. Also have at least one big fan exhausting fumes, as well as any nearby walls or gear covered with drop cloths.
7) Strap on PPE including mask, eye protection, gloves, and crappy clothes. Have at least a dozen pairs of gloves and at least one roll of paper towel on hand. Also very helpful to have excellent lighting under the truck. I used a headlamp as well as the typical work lights.
8) Fill quart containers with WW and put them in a bucket with really warm water as it sprays best when nice and warm.
9) Remove all body plugs. IMHO you must remove the running boards to access a few of the body plugs and really get the rockers coated on the inside well. The running boards are actually mounted to the body, and on my 07 the mounting locations had rusted enough that the running boards had to be removed as the mounts had failed.
10) Start by attaching 360* wand and get in every frame member and where you removed the body plugs. Moving the gun in the clockwise/counter-clockwise whilst sliding the wand in and out ensures best coverage. You should only really need to coat the internal frame members and body once, so make it count.
11) Attach the wand with the straight nozzle and start to spray in all the hard to reach areas you can. I really only used two wands, and didn't spray from the gun directly except for on the gas tank skid. You could see the amount of fine particles spraying straight from the gun tip was producing, and I didn't like the thought of that inside my garage. Plus spraying from the wand really limits the amount of overspray.
12) As long as you are already messy, get out your anti-seize and coat all your skid bolts. Put your skids back on, look for touch up areas. Once you are happy put the wheels back on, and go for a spin to burn off the WW that WILL make its' way onto the exhaust.

 

I tried it one year in my garage with drop clothes and decided not to do that again and now just do it in my driveway.

 

I did my Taco for 10 years with Fluid Film every fall in the driveway. Except this year. Last Friday I took the new to me GX460 to a pro and paid to have it done. Well because it is a Lexus Joining the 65+ crowd may have something to do with it as well. Heck I was sore just dropping the tire and carrying it out of the driveway then cleaning the undercarriage the day before coating LOL.

Well done, your hard work does pay off IME even if you are a bit sore the next day. Or rest of the week in my case.

 

Yeah like I said I can see why people pay to have it done. I said the same after doing a bunch of tile work on our first home and being sore for a few days after.

A friend with a lift would have been perfect and likely have taken much much less time then constantly darting around with the creeper. But I don't have a lift, so I crawl around on the floor.