power inverter install

i'll post some pictures so people know what im working with. Im wondering what the voltage drop on a 10' run is for DC 2Gauge cable. I was thinking of making connections and wiring the truck batteries in with the camper batteries so that the ALT. charges and runs the inverter. the only down side is needing to remember the manually turn the inverter off when I shut off the truck. Im also thinking I could wire a switch into to send power when I flip the switch and **** off when the truck shuts off to prevent from draining the batteries. this is all new territory so being guided in the right direction helps. Im pretty well set on installing the dorm fridge, just trying to figure out "How" and "How to" power it.