how cold is too cold?

ok, so maybe the snow picture is a little overkill. but, i checked the weather for both mancos and grand canyon (since both are places where we will be camping in 3 weeks) and night time lows are already in the 40s!!! i suppose this weekend will be a semi-trial camping-trip-with-a-toddler, since the expected lows for glendale springs is only in the upper 50s. not really that cold, comparatively. yesterday i bought k a pair of jogging pants and a jacket and long sleeve shirt. thinking, he may need it but he probably wouldn't. well, maybe i need to take him 2 pairs! and maybe i need a pair for myself! (pregnancy heat will take you far, but not THAT far...) i wish he'd wear hats, cause a toboggan would help keep him warm. and as for sleeping arrangements, that is the biggest test part of this weekend. i know we both can't fit in my mummy bag, so i have to find away for us to sleep together (lucky me, sleeping with a miniature version of my heater-husband). do i revert back to the not-so-warm old school types of sleeping bags? maybe i can make a homemade version of the two person sleeping bag (zip 2 rectangular ones together) to have room for both of us! and, as for a pad, what do i do there? the rain out today is keeping me in. but, maybe tomorrow (or friday) i can venture into my least favorite store and see what kind of cheap-o large-ish pads they have...