yes and no.
watts is a power measure; connecting up a set of panels in series will result (assuming reasonable matching of output parameters) in greater output power than either panel can achieve alone.
the question makes more sense if you ask about the output current; but you are correct in thinking that the panel with the lowest output current sets the limit for the entire series array.
In your case, connecting the 175W and the 165 W panel would give an array of about 330W at 48V. in reality, even discounting all the weather and loading curve fudge-factors, you'll achieve somewhat less, becasue some of the 'lost' power from the bigger panel will heat up the smaller one, reducing its efficiency. I can't tell you qualitatively how much effect you'll actually see without knowing a lot more than I do about your panels. . . . and even then it'd be a guess.
I'm not sure that adding the 10W panel will ensure perfect matching with the 175W panel (too many variables unaccounted for) but it can't hurt.