how can you have longer track rod ends?
the limit is the gearing in the rack, everytihng else is missing the point

as for the arb getting in the way, you also need to look at where the chassis rails are, because they will be the next limiting factor

what you want to do to achive greater lock is to move the pivot point of the tre closer to the hub, but thats going to be a bit difficult as you would need to have custom hubs made up to play around with to see which was the best AND you would have more load on the tre because it would be doing more work and the leverage owuld be less

lots of intresting points ocming up for sure, but you need to be able to get more lock before you think about what you are going to have to move in order for the wheels to avoid hittings certain parts of the rest of the car