I was wondering if anyone could let me know how the sizing is for these. Are they over sized enough to fit over baselayer and pants or are they an athletic cut? I own a pair of thermawrap pants in a medium, which should be my size, but they are very tight and compress at my thighs when sitting and provide no help insulation.. I'm basicly wondering if I should order my size or go up one to accomodate for extra clothing? Thanks