The problem is the 12v socket with its 8a is not enough power to plug the inverter in. So the inverter needs power from the batteries which can mean it must be close to them, while the 120v line to the Tv set inside is far away from the batteries. So a long 120v extension cord has to be passed through an open window or door, which lets all the mosquitoes in.
So the various cures come into play to get it wired up so you can close the door and windows while watching TV! What you do about that depends on the floor plan of your rig as much as anything. Finding holes or drilling holes to pass wires is all part of the fun.
About then you join the many who wonder if the people who design RVs have ever gone camping in one.