If your only wanting a mobile PW but bolted into your van, why not just keep it mobile?
Most of the skid mounted washers are 20 something horsepower, and heavy, and large, hence why they are skid mounted, because you wont/cant move them.
If you only using a smaller engine, keep it mobile, leave it in the van for jobs, but you have the option to take it out. decent hose reel (on wheels or out of the way in the van) Tank. simples.