While you may have lots of room behind the tank in THISplane, many planes do not have room behind the tank. As has been said before above, this just isn't a good idea. The reason nobody has done this before is it's simply not something worth doing. Trust me, if there were merit from having a fuel tap on the back of the tank Dubro would be selling one like that. As others have said, you can drill a hole in the tank and try to run a line through it. As others have said, it's going to be a weak point in the tank and will probably cause the tank to crack and fail. As others have said, you will have problems getting the tank to seal properly, which will result in fuel in the compartment with is not good for the wood and glue joints in the plane.

If you insist on having the fuel dot in the plane then do as you indicated in your first post, run a line and come around the side of the tank to reach your fuel dot. There is no harm in doing this and won't affect how anything works.I've done it before in several planes and it works fine.

Or, if you dead set on having a tap on the backside of that thank, pull the tank out and turn it around and install it with the bung in the rear of the compartment.

Ken