Run, don't walk down to Midwest Mountaineering. They have some Western Mountaineering sleeping bags on sale for 20 percent off. Unheard of! A twenty degree bag should be good for early Srping and late fall here in MN and can be opened up as a quilt for warmer weather. If you are really serious, drop the bucks for one of these bags. If you aren't sure yet, go for something like the Campmore 20 degre down bag.
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If I wouldn't eat it at home, why would I want to eat it on the trail?