But how are you getting the water OUT of the fuge to go in to the bulkhead? Are you going to use a pump or is the fuge going to sit higher and gravity will jut let it flow back with each tank having a bulkhead and a piece of hose connecting the two? If you are "t"ing off to supply the fuge and letting it drain back via gravity it should work fine. I would suggest having only a small difference in heights though. You don't want a waterfall coming from the fuge--h20 level will always be low and it will wash things out of the fuge. An inline checkvalve may be good as well, but someone else could maybe answer that one.
Make sure you do have one baffle to keep macro and snails etc from entering the bulkhead, but you don't need three as a bubble trap. Sorry for the confusion on that.
"Cute" cycling? I'm not sure if it would affect your tank in a negative way because you are just adding a larger water volume. This makes thing easier, but you will still get a cycle but it would just amount to greater dilution of byproducts. Like pouring a cup of bleach in a tub or pouring a cup into a swimming pool--still one cup, just much more dilute. Really shouldn't matter though, because you don't have any animals in your tank yet. I don't feel it will speed up or hinder any kind of cycle.