What everyone else has said, smoking and driving is a definate no no. No clue what arizona is like, but in london if your in central london with no where to smoke inside or in a park, you go of a main road to the streets that run parallel to them and walk taking a turn each time you can without turning onto one of the main roads constantly moving. Often these roads have things like fastfood places or restraunts or ocassionally a pub. There are people walking around and will look disaprovingly if they spot you but won't call the police since your walking. What are they gonna call them and tell them. "There's a guy with a spliff on this road", "how long as he been there" "30 seconds.... he's not actually here any more" Enough people on them for it not to be immediately obvious where the source is coming from so if anything is up you can chuck it carry on walking pretend like it's not you, get on to a main road and you're pretty much free to walk into any shop dissapear. But people in london rudebois smoking weed isn't too uncommon a site in london, I would find it hard to believe tat even the type of people that would call up the police would do if it wasn't outside there house. Don't dress like you smoke weed as well, that will make a big differance. Also British laws are more lenient.
But yeah find the nearest park then commute there on public transport and eat lunch whilst commuting if you feel like your short on time.