A few good suggestions have been made. I agree that a #4 or 6 AWG lead from the battery is about right. I would go with the #4. I would also install an inline 30 amp fuse upstream of the distribution panel or positive buss. A separate fuse for the inverter is not a bad idea, either.
Some of your loads seem a bit high. I'm guessing much of the hardware
is a little older (incandescent lights, older auto pilot, that sort of thing). I would look at upgrading to LED cabin lights and maybe a newer auto pilot. My Ray Marine ST1000+ only draws 185 mA and it took us to Hawaii
on a Moore 24 last summer.
So, bottom line: #4 AWG from the battery to the panel with an inline 30 amp fuse ahead of the panel. If you use the inverter, then an line fuse for it, too. Otherwise, why not take it out? Oh, yeah...a good non-conductive dialectric grease on all connectors on the back of the panel. It will prevent corrosion
and keep connectors clean (thus reducing the resistance and load on each circuit).
Enjoy sailing your boat