Checco, I don't know the bags you are talking off but I would go the military route. Just don't stuff them super full so they don't look humongous. Also try to pack them in a way that they don't bulge and have nice clean outlines. That looks less bulky to the eye so you are less likely to raise a red flag at the check-in. And make sure you pre-check and pre-pay for the luggage. It's cheaper and they will be much less likely to bother and make you pay extra fees.
One of my jeans weighs 730 grams. We are talking Levi's 501 in 33x32 size. This should give you a pointer. Sweaters weigh around 500g. So 10 sweaters shouldn't be more than 6kg and 10 jeans shouldn't be more than 8kg in those sizes. As you see you can pack quite a lot. Read the packing sticky on top of the forum for info on packing techniques. For your endeavor I clearly advise to go with bundle packing.
Hope that helps. Have a safe trip!
Bruno, the 25-26" suitcase are indeed about as big as one can get in general for the 50lb limit with a normal combination of packed items. When we still had the 70lb limit bigger suitcases made sense. Now not so much anymore since it would take light but bulky items to fill them to capacity but not go over the weight limit.
Till