Should be easy to connect the rear tank to the front main drain. Here are pics of my modification to do just that.



The rubber couplings are for the possible time that I need to access the slide mechanism. No big drainage problems, depends on how level front to back. Usually just a cup or so of kitchen gray water remains in the pipes after dumping.
Many others on this board have done this also. Sorry, but I don't feel like carrying too many hoses and connections when a simple modification can make life easier!!!