fuse distro box

I need to get control of my battery terminals. I want to make a distro box in addition to the factory setup. here are my thought, let me know if im on the right track or have any ideas on it. this is what i need it for: kicker 2500.1 (might upgrade to a 5500W crachendo), eclipse amp 4X 40A fuses (not sure of model number), 50A off road lights, 5KW power inverter, 16,000Lbs winch rated to pull 380A (6HP motor), starter, and a few various other small draw components. i also have a second factory battery that im not sure if i want to put into this distro or direct to the battery itself. i have plans to add 3 more batteries under the vehicle about 8 feet back from the engine compartment. u would take a plate of brass and mount it into a rubber box, ground and positive from the batter will be maybe 1ft long and go directly to the terminals. i do not know what thickness of brass i would need but i assume its 3/8" or more. i would tap out holes in this brass plate and use a rigid plastic bar running parallel to the edge of my brass plate and on that have mounted aluminum threaded adapters to screw posts into. i would run fusable links from tapped holes in the main brass plate to the corresponding holes in the plastic bar and screw down my wires into the plastic. id seal the top with a clip on or something cover and silicone around all the wires entering the rubber box to make it water tight. the truck has a water proof drive train and a snorkel so submersion is likely of this box. thanks for the help.

anyone able to tell me how thick a plate i will need for this kind of amperage draw? and if i should use copper or brass or aluminum?

I'd suggest looking into the need (or otherwise) for battery isolation before considering plate interconnections.

i want a fuse distro box. i do not want to have all these wires on the terminals of the batteries. i have 4 batteries in the system and have no plans to isolate them currently. 2 batteries for only starting and 2 for the stereo just wouldn't work well, i would need 3 or 4 for the stereo/power inverter plus 2 to start it. it would require to much to isolate and i dont see any major benefit. either way i will need a fuse distro block.

You can parallel as many as you need. The non-paralleling is when not being charged or used so that one bad battery does not wreck the other (three). However as I just wrote elsewhere, undoing interconnects/links is a common method used by some (but usually not if on a daily basis etc). For 4 batteries, it is merely 3 relays which can be manually connected or automatically when charging (eg, via the charge light of a voltage sensing isolator). There is also the connection geometry for parallel batteries - eg, for 2 the -ve/GND is off one and the +12V is off the other battey. For 3 & 4 it gets more complex if long-term use without recharge requires balanced battery discharge. I'd avoid Al for automotive purposes and stick to copper, especially if cables can be used.   

k, so would a 2X6" 1/2" copper plate be able to handle this kind of amperage draw? could i use smaller or larger? the batteries are all parallel at this point. the vehicle is factory setup that way with 2 batteries stock just linked with a 00ga power wire and grounded to the frame. from there its stock alternator puts out 236A @ 2100RPM. i dont intend to discharge the batteries to far. i currently run 1300CCA group 31's.

6" x 1/2" is good for 2000A (up to 30°C rise) according to StormCopper's Ampacity Chart for Copper Bus Bar Design. Undoing such busbars should be fine for log-term isolation of the parallel batteries when not in use.