Lets start with lessons...
There are a number of lactose-free cheeses. Cabot and Cracker Barrel make an extra-sharp cheddar that is lactose free. It appears that most, if not all, of Cabot's cheeses are lactose free.
Quinoa takes a long time to cook, and is difficult to prepare because my jetboil... well, boils. Simmering is not an option. I kind of have to boil for a half a minute and let it sit, covered for a bit and repeat. The process takes like 20min, worth it, but I have to plan ahead and watch my fuel usage.
Hormel pepperoni is gluten free. Add lactose-free cheese and a corn tortilla and you've got a great high-calorie meal/snack.
Okay, exceptions...
I have found that chocolate is magical! I have yet to turn down chocolate because it was milk chocolate, especially when it's free! I know I'm not supposed to eat it but... c'mon! It's chocolate!
Oatmeal. I eat two packets almost every morning. Some people with a gluten intolerance tolerate oats, I guess I'm one of them, because I've been eating oatmeal virtually every morning. No noticeable reactions so far. And, boy, it's nice to have a warm breakfast.