It was installed before the engine went into the hull... If you can't reach it with extensions, socket ujoints, little kid hands holding a custom bent wrench, etc, then it might be an "it is what it is" situation. You're the one looking at the bilge and the limitations it's presenting you, so use your imagination.
Unfortunately, It's not the first and won't be the last time someone couldn't get at something they needed to get at in a boat, without removing something. Just in your case, it's something really painful to remove.
