Hi all,
Firstly if off set then you do get visibility down the site but it limits manouverability on teh other side and as (other) Alan said it will limit monouvering in tight spaces, which is why I now have mine centrally mounted.
Making it!! First one on Landcruiser Colorado. I removed the towing hook from the front section of chassis and cut a piece of 50mm angle to fit under it using same spaced bolt holes. To the vertical face of this I welded a length (about 300mm) of 50mm box section angled (so that when extended it just cleared the front bumper and was at a height similar to the rear ball). I then cut a piece of box section (that was just big enough to fit tightly inside the 50mm box) long enough to run the full length of the welded section, clear the front bumper by enough to give clearance. In the end I then fitted a simple bolt through towball,(but strengthened the end so the the box section was not compressed by the ball). The two sections were then held together by a quick release bolt. This meant that the front of the fitted part was about 200mm clear of the front of the bumper and tight up to the chassis.
On my current landcruiser there is no chassis in the same way so I had to make to hangers of 50mm angle that bolt onto the front bumper mountings,using existing bolts. To this is welded a 50mm box section across the width of the car. In the centre is a piece of 50mm box welded at right angles with large triangular plates strengthening it in both planes. I then use the same insert with the ball on it.
Whilst these have worked extremly well on both vehicles they are totally differnt so making one for your own vehicle would require a design based on the underside of that vehicle.
I hope this helps and if I can help in any other way I will try, it's hard to explain solely in words whena diagram would show clearly my designs.