The two T-1275s are connected to the 2000w inverter using only the inverter's twin set of cables. One set to each battery. The cables also act as the parallel links between the two 12s, so no extra wires needed for that. I have no ground wire to the frame either, since there is no need. The two batts only run that inverter, nothing else.
This is all in the trailer, but as a stand-alone package, it could be in the truck bed or anywhere handy that a 120v cord from the trailer can reach.
http://www.ebay.com/itm/VECTOR-VEC085D-2000-3000-WATT-3FT-POWER-INVERTER-CABLES-/320559970754(relates in a way to the topic of remote power stations you can place near the rig)