First of all, I don't have (or know much about) a battery switch, and I'm sure many on here may disagree, but with your setup I'm not sure why you really need one. What are you wanting it for?
I've got basically the same accessories that you show. For the nav lights, bilges, and fish finders: I ran positive from the cranking battery, to a circuit breaker (no more than 7" from battery), to fuse panel, to switch, to accessory. For grounds I added a negative buss bar like you show. Everything else I ran to the trolling motor (TM) battery the same way (battery, breaker, fuse panel, switch, accessory, with another negative buss up front). The thought here is that your "essentials" are on the cranker, and your "optionals" are on the TM (house) battery. You don't want to treat your cranking battery as a house battery, that way the cranker is always there to get you home. The fish finders, although optional, still go to the cranker because hooking them up to the same battery as the TM may cause interference when it's on.
On your diagram, you don't show circuit breakers between the battery and the fuse panel, so you don't have any protection for that run. And I'm not exactly sure how you're running only one wire between the fuse panel and the switch box, but I don't know what kind of switch box it is and that might be fine. Your TM ground should be directly to the TM battery, not the buss. You might want to wire your bilge up so that it's both float and manual via a switch, and you could save a slot on your switch box by putting your nav lights on a DPDT (on/off/on) switch.
Hope this helps.
RR