Brian,
I'll offer this bread crumb, and hopefully it will lead you to the entire loaf of bread. Depending on how the toilet's components convert to GDL, it'll show up in the 3D script as a MASS or a COONS or as primitives, as well (like PGON, EDGE, VERT). Depending on what you get, you may be able to control it's masking.
If you look in the GDL Reference Guide (in the Help menu), you can read up on the above shapes (or ones you find in your object). In the first couple of lines of code for each shape described, you'll be able to edit a numeric value to control display of vertices, edges, smoothing and visibility of sides; or edit some code in each line (the status code) to get what you're after. WARNING - could be TEDIOUS.
I'm not 100% sure, but this could make your objects have full functionality in all views... Including how it looks using a PROJECT2.
Take a look at that.... I've actually printed the GDL Reference Guide and keep it in a notebook at my workstation for those code hacking moments. Sometimes, It'll take some experimentation and patience, but stuff you learn is yours to keep. I can't give exact advice without seeing the object your working on, but I think looking at the general concept of masking and status codes for whatever shape is described might do the trick.
I did this once with a Victorian bathtub object. I had to hack a lot of code, but I made the thing smooth and clean.....
I just looked at it... It's an XFORM made out of VERT's, EDGE's and PGON's. I can see where I hacked the status codes of the EDGE's.
Hope that leads to a kernel of a solution for you... For myself, it would be imperative that the object 'work' in a 3D view, like a section or an elevation.