Mike,
Thanks for explaining your proposed location. I agree that the drainage ditch would probably need to be relocated in order to have a large enough flat pad for the section house.
I also think Stephen P. is spot on as well - the section house, prototypically, would be located along the mainline, not in the yard. I do like Wayne's location, north of the water tank.
Any structure located at TOM would need to have all four walls, with a locking door; while access to TOM, at present, is via a very rough access road, hikers, etc. could cause mischief.
Dave Crow