first off, you dont need to fuse grounds, second drop the distro block for the 1000.1D's just get 0-4g reducers, itll lower the resistance in the line and allow your amps to get a tad bit more power(thats just the way id do it personally, to each there own, itll also be cheaper)
third, you CAN do the cut off switch, but i personally like using the PAC LC1 bass knob, its an inline rca bass knob, i dont see why it wouldent work with two amps
and idk where that 3rd run of power is going at the top, just seems to be gone lol
oh and run the 4 channels off the rear batt aswell
and me personally, i ground the back battery to the frame aswell as running a ground from the front, some do some dont, again to each there own
edit: im uploading a pic now of what the best way to do it is, minus the reducers for the ease