You could hook it up the way shown but as Darwin points out, if you did, removing the battery
would stop 12v to the rest of the trailer.
In practice, the converter/charger and battery usually both go to common posts. + from the converter and + from the battery to one post on the fuse panel and likewise the negatives share another post on the panel. This is the parallel hook up that Darwin talks about. That way, removing the battery still allows the converter to supply 12v to the rest of the trailer. And it still allows the charger/inverter to recharge a battery when one is hooked up.
I believe, but I've not checked my set up, that the + and - from the Tow (when present) also hook up to the common posts as well.