The Anderson does set the trailer back either 9.5" or 5.5" depending on how you install the king pin adapter. Either way the weight on the center of mass under the hitch remains the same. This is true for the center gooseneck mount or the rail mount (if the rails are installed correctly) You can turn the adapter on the pin box 180 degrees to shorten the length 4". But you can't turn the hitch 180 degrees as the pin that hooks the trailer up is offset 5.5" to the rear of the trucks center gooseneck ball and the frame of the hitch is designed to fit over the crossmembers of the truck. Either way the weight of the pin box is still applied to the same center as a regular fifth wheel hitch. It's funny some times when folks feel having a longer pin box will move the weight of the trailer further back in the rear of the truck. A longer pin box will add strain to the trailer frame and pin box frame due to the laws of leverage, but the hitch weight will remain centered in the same place.
On a short bed 3/4 ton truck the Anderson is great as you can put a hitch on the truck that can tow more trailer than you can carry for under 100 lbs including the gooseneck ball and safety chains. And do it at a cost of under a grand. Just make sure you get a trailer with a "short bed" nose on it so you can turn it. And then be careful to not tear up you cab.