No worries. The original pipe is black 5/16” nylon, which had brass ends to fit to the tank. I decided to replace the black with clear nylon as the original had been chopped short by the previous owner. The clear nylon I have used is 8mm and I like this as you can see if there are bubbles in the fuel (mine is diesel). The new tank and sender outlets and returns are 8mm, so that was another reason to change to new pipe. I used rubber fuel grade pipe to connect to the new sender and tank connections as it worked better for me than using brass connectors. (I needed a bit of deflection in the hose to route the feed correctly). I joined the rubber to nylon using brass inserts in the nylon tube to stop it crushing and fixed with Mikelor clips. I have larger ones on order to replace the hose clips. I used mikalor clips as they are much stronger and unlikely to leak.
With the electrical connection, the original was fitted in the same manner, in the same place, albeit with a different type of box. I have used these boxes many times in HGV’s and tractors mounted on chassis with good results, so I’m hoping this will perform as well here. Understand what you are saying, and I agree that there would be an option to fit internally. I just chose the convenience of mounting it there.