Hi!
I think that a colony *prepares itself* for winter and ensures the conditions for its own success. If these conditions are lacking it is very difficult to simulate them. I combined many colonies last fall and I must say that the effort was mostly wasted.

you wrote:
1.  Just feed them additional syrup with a pail on top and try to overwinter them above a strong colony.
        -- feeding won't make up for lack in colony strength

2.  Unite 1 light weight colony with 1 strong colony (newspaper method).
        -- this is really the only option, though may be a waste of time.

3.  Unite two light weight colonies together to try make one strong one(newspaper method)
        -- complete waste of time. two zeros add up to one zero.

4.  Give each light weight colony a new queen( I have some mating nucs that I could unite them with), and then feed them additional syrup.
        -- may be worth trying but if the unit is not storng you'll probably lose it, new queen and all.

        the best tactic for weak colonies is to shake the bees out and store the equipment. a weak hive is probably mostly old bees and have little to add to any other hive. the time to prepare for winter is in the summer, requeening and such. by fall, the die is cast. some will not make it, and there's little to be done.

peter