Re: DIY combination potty/shower?
if both your black and grey water are in one tank, you can just put the toilet going to the large 3 inch line going to the tank with the 1 1/2 in shower, etc grey water lines in the 3 x 1/12 tee under the toilet.
otherwise if you have separate grey and black water tanks, you can put the toilet anywhere it will make a pretty straight run to the black tank.
Jesus Christ... Conversion in progress.