Just get the ball valve. Walking back to the truck should only be done once per job if you do it right. Sometimes I like to use the soap nozzles to rinse.
I started my setup with this thanks to @Innocentbystander and I am glad I did. The injector gets rinsed which is an additional benefit. As mentioned already, when the process is well streamlined, not too many trips needed back to the truck. A cheap DIY remote is easy to set up until a more expensive unit can afforded. Xx15 nozzle is around 250 psi with a 4 gpm unit. Not what is referred to as soft washing here. Higher chance of disturbed oxidation on vinyl, etc etc. The 3-way valve and rinsing with soap nozzle just makes a lot of sense.
Dude you need to upgrade, the black one is so much better. I have three dead blue ones sitting on my bench at home. I went through six in two years and finally had enough.