Electrical Conundrum -- Parasitic Draw

[MobileCabin]

Somewhat related to the Parasitic Draw is how to fuse and add a cutoff switch. In an application that I have I need to add a cuttoff switch to turn off both the connection to the inverter and the power going to the dc distribution. I have 4 AWG going to the dc distribution with a 50 A Eaton breaker just before the dc distribution box (PD6000). Then I have 1/0 AWG going to the 1K inverter (less than 18"). I need at least at least a 150 A T fuse for the inverter feed. Now I would like to add a simple Blue Sea m-series on/off switch.

1)Can I go from battery to 150 A T fuse to m-series switch and then from there to both inverter and dc distribution?
Or
2)do I need an additional switch for a 50 A fuse off battery to that switch and then to breaker?
Or
3) 1) but with a 50 A fuse off switch and then to breaker by panel?

Thanks

[booster]

Rule of thumb is every wire needs to be fused at it's power source to protect it at capacity. If you wanted to do what I think you want to do, you would have a 200 amp fuse on a 200 amp capable cable to the Blue Sea switch, and then coming off the switch you would go to a 150 amp fuse and cable to the inverter, and also a second wire off the switch to the 50 amp breaker to the coach. The 200 amp should be as close to the battery as possible, the other two as close to the switch as possible.

[MobileCabin]

booster

That makes sense. No issue with 200 A t fuse near the batteries but I might have to start rethinking location of switch to make room for the 2 additional fuses.