planning to make a portable watering system.

[GARDENALLDAY]

instead of having to use the hose all the time, which can get messy and annoying....

I'm planning to make a portable watering system. Similar to a rain bucket but perhaps putting it on your back. and having a small hose with a water valve and a spray nozzle

[Eeyore]

That's an interesting thought and no reason it isn't possible considering that you see those city guys with their spray canisters all the time. There is probably something available already or something easily adaptable to your purposes.