There are probably several different ways of doing what you want. I will tell you of our way. I will try to make it simple so let's just start with the inverter (ours is 2000 W) which is wired to the battery bank in the front compartment of our fifth-wheel. [we have solar and lithium batteries, but I will leave out that part and just start with the inverter.]
We have hardwired from the inverter to a normal 30 Amp outlet which is open to the outside of the trailer. This required a hole and a cover for the outlet:
OutletI could go into much more detail and if you PM me I will be glad to answer any questions. But this is how it works. I simply use the regular 30 AMP cable and plug into the inverter just as I would to a campground pedestal. Everything in the trailer is "live" just as it would be in the campground. Of course, I cannot power everything, but all my plugs are "live", my TV is live, my refrigerator and heater are live [if I have enough battery to run them.]