That "map was dead on after 12 years" line is nice and all, but come on, one Sharpie map holding up doesn't prove hand writing beats a printed label. Half the cans I open have Sharpie scribbles that faded to a gray smudge, or the guy wrote "kitchen" on a zone that turned out to be the garage outlets. For every good one there's ten where the writing meant nothing or the panel got swapped and nobody updated it. What actually saved that job was somebody labeling things right and then nobody messing with it for 12 years, not the marker itself.

So you changed two things at once and now you're sure the foam pad was the reason? Bare ground pulls heat out of you way faster than snow or a tent floor, so of course the second night felt warmer, you were on a totally different surface. And $12 foam pads come in different thicknesses and densities, some are basically packing material. Did you run the same pad on the same ground on back to back nights, or just compare two random trips?