I base my campaigns on the standard rations of the British soldier for a century or two:
One pound of wheat bread, or one pound of flour, or one pound-and-an-half of rye bread, per man, per day.
One pound-and-a-quarter of beef, or one pound of pork, per man per day; or one pound of beef and one pound of pork for two days, usually salt beef or salt pork.
Three pints of dry beans or peas, per man, per week.
One quart of beer per day.
Six ounces of butter per man, per week.
One-quarter cup of rice; or one pint of cornmeal per man, per week.
2 ounces rum, per man, per day, when on fatigue duty.
From my readings of the era, this was considered enough to keep the men able to fight, but it was also considered to be barely enough and certainly was not considered adequate for the men to be happy for more than a short time. Whenever possible, soldiers would grow vegetables and hunt. If they built a fort, they would plant fruit trees, hire women to cook for them (some of these women could be hired to move with the soldiers and cook and wash for them, yes cook and wash--prostitutes were drummed out of the camps).
I've done hard work from time to time, and I can see how the above rations might be considered borderline.
Living "off the land" was very slow business. Rangers and light infantry who could get by on less were elite troops (aka PCs).