I was able to get my food down to just over 1 liter/day (~3300 calories/day) by being extremely rigorous about choosing food with very little air, using a bulk-packaging approach and eating lots of fat. I got 10 days into my 11.5 liter BV500. This means I would be able to get 6+ days into a 7.2 liter BV450.
Another way to look at it is I got ~33,000 calories in 11.5 liters, or 2,869 calories per liter.bthis would seem to predict that you could get 20,660 calories in a BV450 which would be 2582 calories per day.
Tipi’s suggestion is not a ludicrous as it seems… Packaging meals in larger quantities in loose bags is much more space efficient than individual meals rolled up into ziplocks. If you could stand it, you could have oats, instant hummus, polenta, couscous, mashed potatoes in larger bags (produce bags from the grocery store work well) and eat them with lots of olive oil or ghee.
You can increase the caloric density of nuts by melting dark chocolate (enriched with extra fat… Coconut oil works). Cast it in a solid disk or break and the break pieces off.