I dont know how involved you want to get here, but when I had to replace the lines going to my tanks cause the metal ones were rusted through, I just ripped every single one of em off to the selector valve, and stuck on rubber line with good clamps. If I had to do it again Id completely take off the selector valve to make it easier to plumb up the rear tank. Make sure you take your time and make for 100% sure you know which line is which, I dont know if it matters, but I did so I didnt have to try to figure it out if i got one switched. Also when I did mine, the midship tank was the easiest, I can see the top of it by sitting up under the bed. I think the hardest part of it was removing the factory retaining clips on those plastic lines!
I didnt go ALL THE WAY to the sending unit on the rear tank so all that I did was cut the plastic line and pull back the factory rubber sleeve around it, and simply slide over the rubber line, and clamp!
I would suggest if you only want to get under their and take a diesel bath once, I would just do the WHOLE system all in one shot, just simply rip off every single stinkin factory line all the way up to the lift pump. I dont know what you plan on doing with the metal line that goes from there to the filter so use your own judgement or creativity.
But thats just my 2 cents, I got a hell of a bath when I did mine because of what I was dealing with.
but you do it your way, the only thing I will suggest in the parts department, is make sure you have the right size clamps, and in stainless steel. I just had to replace one of them because some how it worked loose, and was broken! it was the wrong size clamp, but still!
Oh and you want a clamp on every single splice/connection, otherwise it will leak like a siv!
putting it right by the valve would be the best case but hay then again I say whats wrong with the factory pump that lasted 180k 
