Canned coconut milk and vanilla protein powder. Quick and easy to mix, and it tastes great! If you have friends who'll be letting you stay at their houses, eggs and sausages are also easy options. You can also go to just about any "breakfast" sort of restaurant and have eggs cooked in butter. Make a huge batch of paleo trail mix and bring it with you for the road. You can order burgers without the buns at loads of chain restaurants. Lots of steakhouses are open late, too. If you have to sleep in the van, canned tuna packed in olive oil with chopped avocado is easy and decent-tasting. Bring lots of beef jerky with you!
In a pinch, Walmarts and gas stations will usually have Larabars and some decent trail mixes (be careful of these; they often contain nasty additives). Fruit is almost universally available -- you can get bananas, apples, and oranges almost anywhere. I know you're trying to lose weight, but it is BY FAR better to eat fruit while on tour than eat processed, chemical-laden garbage. If you absolutely MUST, make a meal out of bananas.
As far as stimulants go, stick to tea or coffee. Don't load up on Red Bull and other energy drinks; totally not worth it.