This doesn't address cooked (or vacuum sealed) bacon, but raw bacon instead:

"Randolph B. Marcy's A Handbook for Overland Expeditions was considered by many as THE manual for westward migration. Originally published in 1859, it contained practical advice on everything from route selection and wagon packing to emergency medicine (rattlesnake bites) and dealing with Native Americans. Marcy [1812-1887] was a captain of the U.S. Army. Prior to the Civil War he served in the West, forging new trails and escorting wagon trains. That made him an expert in stores and provisions. In his own words:

"Supplies for a march should be put up in the most secure, compact, and portable shape. Bacon should be packed in strong sacks of a hundred pounds to each; or, in very hot climates, put in boxes and surrounded with bran, which in a great measure prevents the fat from melting away. If pork be used, in order to avoid transporting about forty per cent. Of useless weight, it should be taken out of the barrels and packed like bacon; then so placed in the bottom of the wagons as to keep it cool. The pork, if well cured, will keep several months in this way, but bacon is preferable." http://www.foodtimeline.org/foodpioneer.html

The bacon referenced here could be different from what we now consider bacon to be in the U.S. Certainly, the older use of the term referred to pork in general. But note in the passage that cured pork is also referenced...this indicates to me that the bacon reference could indeed be something similar to today's bacon...especially the line about the fat. Whatever...the bacon of that day undoubtedly had less preservatives than what is used today (but maybe more salt?). FYI, the wagon train trips generally took 120 to 170 days depending on the destination.

Remember, temperature affects the time to spoilage, it doesn't cause spoilage. Heat can speed up spoilage but only because the bacteria or other buggies were already present or the food became contaminated after opening. Hygiene; protecting food from bugs, avoiding cross-contamination, hand washing, etc., allows food to last a very long time.

FB