This may sound crazy, but it could solve your situation. I just modified my toilet to mount the tank 6 feet high. It is just an experiment, but will allow me to put the toilet into a corner 45% from either wall. I did it with 60.00 worth of hardware store stuff and 1 1/2" ID clear tube. It makes more flush pressure and looks very 'funky'. And a side benefit is that I can see if the flapper valve is leaking because a trickle is running down the tube.