I have a Dodge that does not use spark plugs and it is so cool! I would get the tandem axle trailer with brakes and get the brake controller professionally installed. With two axles the trailer will ride smoother and it will not be as bumpy on bad roads. Without brakes and the tank full of water with this light truck GOOD LUCK TRYING TO STOP QUICKLY! Let's do some math:
300 gallon tank- about 125 pounds for the tank and 2400 pounds for the water @ 8 pounds per gallon (more or less), Pressure Washer 750 pounds, fuel in the unit when full 80 pounds (more or less) extra fuel cans with fuel?,
p.w. hoses (supply and pressure-100 feet of each) 30 pounds, cleaning chemicals in the trailer? Wands, brooms, brushes, etc...., Surface cleaner?,
All this adds up quickly when you add up the things that you might not realize. What is the weight of the trailer? The weight of the trailer is part of the capacity. Example: My trailer is 7000 pound capacity but the trailer itself weighs 1100 pounds so I can only carry 5900 pounds and it will be at the limit but you don't take it that far. lets add this up: 125 + 2400 + 750 + 80 +
30 + = 3385 not including the weight of the trailer or accessories like chemicals, extra fuel, wands, brooms, surface cleaner, etc... It all adds up.
You can get the trailer with two of the 3500 pound axles and that gives you a lot of room to grow. A while back there were two buddies of mine that bought boats on sale and used their old trailers and I mentioned to them that the boats might be too heavy and they should check the weight of the boats and the capacity of the trailers. Did they listen? NO. I got to see their boats lying in the middle of the highway blocking traffic as the weight was too much for the trailers and the trailers finally gave. VERY EXPENSIVE LESSON. If you were to have the same problem and you had to go get help do you think anything would be left in your trailer when you got back if the trailer was still there at all? Not trying to discourage you but these are things to think about.