Others will be able to better advise you on secret dehydrator recipes for your bulk-prep, but I'm happy to share my dirtbag in-town grocery store approach. Are there other things you're mailing yourself along the way besides food? You might be able to forgo the expense of shipping and not tie yourself down to post office hours.
My appetite and taste tends to get a little weird after several hard days. I've been happy with a modular sort of dinner slop rotation to get some variety and flexibility.
If you get in the habit of glancing at the nutrition facts on packaging while you grocery shop now, you'll be able to pick out some calorically dense foods quickly on your town days. Calories per gram is easier for me to ballpark in my head from the packaging- it's already there in the nutrition facts header. 4 cal/g is about equal to that 100cal/oz figure others have mentioned.
Breakfast and lunch are usually one continual no-cook meal eaten while hiking: Cafe Bustelo instant coffee, bars, candy, fritos, cookies, dry fruit, nuts, jerky, corn nuts, etc.
Dinners:
+carb-heavy base (pasta/rice side, quinoa, potato flakes, easy mac, la moderna mini pasta packages)
+ powdered seasoning packets (gravy, chili, pesto, stroganoff, dehydrated refried beans, powdered hummus etc)
+ fat (olive oil, butter in winter)
+Powdered cheese and powdered hot chilis.
I find I can put an oz of oil in anything and not really notice it, but the meal gets a decent calorie boost. It's nice to have a mini HDPE nalgene to repackage the oil to avoid leaks. I'll mostly look to the snacks I eat on the move all day for protein.
It took me awhile to realize it but junk food is your friend; it's usually tasty, calorically dense, easy for your very tired body to digest efficiently, and abundant. Salt, fat, and sugar are exactly what you need. The 3-4x cost savings over mountain house is a nice bonus too! Treat yourself to some fancy bars, a deli sandwich, or scratch whatever weird craving you've had for the last week.