I think you are maybe confusing straylining with what is called a running rig (or similar). Straylining is generally when you are floating unweighted or lightly weighted baits back behind the boat and is hard to do on charters with so many lines in the water. It also doesn't work in deep heavy currents when harbour fishing like you will probably be doing. Often when straylining the small sinker is right on top of the hook(s).
A running rig is where the sinker is above the swivel and the main line can run through the sinker when the fish picks up the bait. Your baitrunner function would work well with that style of fishing.
I would probably use your 10kg set if it has 10kg line on it. 6kg line will be too light for a charter situation where an out of control fish can tangle multiple lines. On a charter you are asked to keep your fish under decent control unless it is too large to do so. Nothing worse than losing fishing time all day due to tangles with people who aren't fishing properly. The stickbait rod will probably be too long to be comfortable to use on a crowded boat.
We run charters out of Westhaven and having observed a lot of charter fishing that I expect is similar to what you will be doing I would really recommend that you tie say 3 x 2 hook ledgers with 6/0 circle hooks (put the hook through the bait only once so you don't fill the hook gape and don't strike until the rod loads up properly - don't strike at nibbles). You could easily loose a couple of rigs if the sharks turn up so spare rigs ready to go are good. I would also prepare a couple of short (say 500 - 600mm) traces for a running rig as sometimes the fish bite better on these in heavy current. The skipper will probably tell you which to try first.