Hello, I´m very proud that you visit my country, I´m from Buenos Aires and I can tell you that the time I have traveled to Mendoza they picked us up in a very spacious van with air conditioning, our guide was a professor of the University of Mendoza, who in holidays organized these tours, needless to say, that his explanation about the area was exquisite, the views were worthy of a picture. On the question of skipping food, I don´t recommend it. it´s many hours that this tour lasts and also up there where you can see the peak Aconcagua, it is very cold and it is advisable what includes the tour in food and drink, because in addition to tasting delicious wines of the area, a whisky with ice from the peak and a roast that removes hiccups, as well as have the option of vegetarian barbecue. Anyway, you can always suggest your diet when registering for the guided tour. I hope my comment has been helpful.