not that hard of a project, just be consistent. is your battery(s) under the console or in the stern? your on the right track with a main black & red to a distrbution point and then branching to your various feeds. i would use tinned marine wire & heat shrink where possible. i rewired mine(cuddy) 5 or 6 years ago and only had one failure on an inline fuse i did not know about. as far as guages, i would have rpm, temp, voltage(usually have this on your gps) and water pressure. i hated the birds nest that my old wiring looked like, but after i re-wired, i still had a birdnest, but at least i understood it.
this is a shot of the panel that is usually under the dash on a cuddy, i moved it out to the cabin roof & had a new flap made to cover