In the 3D go to FILE>RENDER OPTIONS>SAVE and obviously give it a name you like. When you want to re-use it, go to FILE>RENDER OPTIONS>LOAD and reload it.
Another option, and this one work best for me personally, is find a mode you don't use (e.g. Watercolour - Personally I'd never consider using "Watercolour" with the default settings), and instead of changing the Visible line mode, edit the mode options for the mode you don't use and overwrite that, and again save as whatever you want. That way you can toggle between "Visible Line" and "your preference" quickly just by changing modes.
I don't see why we cannot "Save" current settings as Custom modes, instead of being limited to visible line etc. it doesn't seem a large stretch, and once set doesn't need to have all the necessary adjustments, just a fixed custom mode.
If you find that you would like to set your settings as default modes, rename the DEFAULT>3D.MRO file (so that you can replace it if necessary), and save your current setup as DEFAULT>3D.MRO