They are all different, and even within the same manufacturer the models can be very different from each other. Most of the time you can find the floor plans by searching on google or on the manufacturer website. It will show you if it has a wet bath, or a potty, or just a space for a cassette potty.
If I had a long bed I would be trying to find a model with separate bath and potty, that's the only thing I dislike dealing with in a TC.
I wouldn't worry too much about the tank placement, they are going to be where they need to be. The dump valves will be in the back. The water fill is usually more forward on a side.
Be advised that when you build a floor on the bed, that means the TC sits that much higher in the air. Depending on the TC you may have to anyway, for cab clearance on your Ford. I did.