We have to put in a new septic system (we really dont have one to speak of at the moment) and with no floor in the barn yes, it makes sence to put a bath in. (shower, toilet and wash tub)
the real issue is having enough fall.
The front doors are AT GRADE! i mean NO daylight under them. So if i want a 4 or 6" pad its either goint to stick up (so i have to ramp it on the inside?) or i have to dig it down (i smell FEL work ) but then if i want a floor drain then im going to have a hard time geting that to daylight as it will be low....
I havnt shot any grades yet but i THINK i have a little (6-8") fall to the back of the building which might be enough to daylight the floor drain in the back...
but for the most part ive got one big flat 5 acer IL farm land tract.