Several years ago - too many to discuss - when I remodeled my kitchen I had a very long run of 4" pipe to exhaust an oven hood fan, so I searched and found that you can buy "booster" fans that fit typical exhaust ducts. They allow you to get good air flow through longer ducts than is otherwise possible. I think if I wanted to do this I would use ducting sold for kitchen fans, and I think it is all 4 inch diameter, plus I would use one of these fans to either supply all of the "sucking" or to boost the flow through the duct.
Smaller diameter piping or ducting would have to have much higher velocity air flow through it, and would whistle enough to drive you mad! I think.
EDIT: note to self: read the post right above yours first! That photo is just what I had in mind, only I would put more distance between the fans.
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