Lunch again is determined on how fast you can build and break down your equipment. We try to like to keep lunches to 30 to 45 minutes. If there needs to be added time it's not a big deal but that at least gives you something to gauge off of.
Dinners are usually dependent on how much time people want to spend conversing around the campfire as well as how long it takes them to get there sleeping situation up to par.
For us the overlanding portion of this is the ability to create a system with your rig that allows for the best wheeling, sleeping and eating situation for your needs. It can be a delicate balance to figure out those three main goals of the trip.
I love to eat and make big meals. I sacrifice weight and space inside the rig to ensure I have lots of food and the abilities to prepare whatever I choose to bring. Back when I had my Wrangler as my overlanding vehicle it was a different story due to space constraints.