Gizmo -- congratulations. That sore jaw feeling probably won't go away until you stop riding your new C5. I was grinning up to the moment the engine started clattering. Bought a second engine which is receiving the SB/GHG magic touch and am grinning just thinking about getting back on the road with it (probably Feb or Mar depending on weather).
WRT dumb mods, it looks like I screwed up the fueling one or more ways. Upside down phenolic spacer; kinked fuel hose; clogged fuel tank filter; or something else in the path to the intake valve. Combine that with not checking compression with my gauge and it was on the back of a tow truck at 4.5K miles. And No I didn't take pictures!
WRT to your C5, I'm pretty sure 2018 is a Euro4 model so be cautious about applicability of any electrical and engine mods you find here. Your lighting and engine controls are a bit different and stricter than most REs here.
If you are looking at luggage, I recommend my C-Bow approach for saddlebags and Burly for tankbag. If you like the Trip Machine saddlebags, I have a C-Bow solution for them.