I'd be hesitant to just remove a black tank, even with a leak. Depends on where it's leaking. If you can seal it back up and keep that as-is, then I'd say go that way. Once you start altering the waste plumbing you better know what you are into. I know I could NEVER just do that with my kids and what the flush down the potty. I need a tank to ensure that there is 'proper flow' from the tank to the dump station..... I could get graphic butt most folks know what I mean.