I recently acquired a commercial metal building (barn) in the country. In order to enjoy the place during extended family outings I would like to build in about a third of the building including bathrooms, bedrooms, kitchen, etc. A septic system is being installed now. I am concerned about cutting and trenching the concrete floor to install a first floor bathroom. Options I have considered are macerator toilet with tub on a platform to allow,and a wall mounted toilet, with tub platform. I plan to install the bathroom along an exterior wall just inside from pipe going to the septic system. I read that macerator toilets work pretty well, but am concerned about long term reliability. I have also read that wall mounted toilets are a problem in residential installations because of long term stgructural stability. I presume though the wall carrier could be piped out directly to the exterior vs. down. I would appreciate any comments about the potential solutions. Also any comments re: concerns about trenching/backfilling slab if work is done conventional manner. Thanks

People trench concrete slabs every day to install bathrooms and kitchens.
Macerating toilets are expensive.
My house has wall mounted toilets that are 45 years old. One is over the slab, the other on the upper level. I have no idea why the upper one isn't conventional. It's 2 x 4 construction with nothing elaborate, just a lot of extra bracing behind the toilets, and nothing has ever given way. Neither is on an outside wall so maybe that's where people run into problems with moisture and rot.
Our tub on slab has a lower level of rough concrete under it and an open wet wall behind it, with access from the boiler room. (I plan to get rid of it; too cold). It's always good to have access because clogs are so common (and it's code). So your tub on a platform sounds good.

Have you been in your metal building in the rain yet? It can be pretty loud.

Wait, I do remember a problem with a wall hung toilet: if one gets seriously clogged, especially some object that fell in, you can't just take it off the wall.