Red is certainly the most attention getting, and fits in the with flame theme the best, but, imo, your pizza is the most attention getting aspect of your operation, so you might not need a red tent.
The best looking mobile operations that I've seen have a consistent color palette for every aspect of the business. The truck color, the oven colors, the shirts, the pants, the hats, the tablecloths, the dishes- everything. And it's not just choosing one color and making sure everything matches it. It's a combination of 2 or 3 colors that look good together. You mentioned Napoli soccer- I think sports teams are a pretty good analogy here- multiple color branding. The only difference is a greater aesthetic awareness. Some team colors look great with each other, but some are incredibly garish.
I could give you some combinations that I like, but, at the end of the day, these 2-3 colors should be your brand.
Once you have your colors chosen, then you purchase everything based on that palette. One thing that's important to be aware of is that if you choose something like red, it can't be every hue of red. For instance, the Napoli shirts are a royal blue, and the tent is navy. Very few people would be conscious of it, but there's a bit more red in the tent (a slight purple-ish hue), and, on a subconscious level, these two colors would clash. You can go lighter and darker of the same color, but you don't want to mess with the hue. Imo, it's better to have a red tent and royal blue shirts then a navy tent and royal blue shirts.
Btw, this tent will never appear without the oven, right? If the customers are seeing the real oven in front of them, you don't need to repeat it three more times on the tent. Once you get rid of the oven, that should let you increase the font for a bit better legibility.
Also, I'm not sure if it's a matter of font selection, but the phone number looks a lot tackier than your company name. I would think about removing the number. People are most likely not going to have a pen and paper at a party- or to take the time to put your number in a smart phone. They will remember your website, though, and, if they want your number, you should have cards in a cardholder available (possibly even on both sides of the tent). It's a lot easier to grab a business card than to either write or type a phone number.