Compared to your arrangement, mine ought to be hammer simple.
I did not know there was a Seatalk I and II; not mentioned in any of my manuals
. I figured since my instruments are all older, they would be compatible.
Sequentially, I have over the companionway
the first instrument as depth
(ST60+), then wind (ST60+), then speed (ST60+), then a cable run to the nav station where I have a multifunction display (ST60, not plus) which is a repeater, and from there a cable to the helm
with the chartplotter. As an aside, none of my cables
except the power cable to the depth
are the standard Raymarine cables
. I made my own with correctly colored 14 gauge wire and the appropriate .110 connectors.