Marrakesh is a touristic city where a lot of foreigners/ non-muslims can be present at any time of the year, hence i don't exclude the existance of certain places where people go to eat during the day of Ramadan. though these places are rare, but they would be the perfect place for you to behave freely, as if you're looking to respect muslims during their month of fasting it won't be that appropriate to take your food out of your bag & start eating infront of them, also , do them a favor & do not wear tied cloths or those that shows parts of your body, specially during daytime, that doesn't mean its ok at night, but at least they would have finished their fasting for the day.
I think you would be able to try fasting, if you want so & if this is your 1st time, just try not to do a big effort during the day, also do not expose yourself a lot to sunshine or you will need to drink, speakin of which, if you keep your eyes, ears & nose away from any food-related thing, you'll do good until sunset.
I am a muslim aged 24, which means i'm used to fast, however i always face hardships in Ramadn's 1st. especially in recent years where Ramadan comes in hot weather.