I'm removing one side of the headlights to save weight. My Glow-Shift gauges require a ground, a positive 12V source switched by the ignition and also a positive switched by the high beams. Since I'll have the open connectors from the headlights hanging in there, might as well just crimp a contact on the ends of my gauges wires, slide them into the connector (with my inline 3 amp fuses of course) and tape it up good so the contacts can't pull out.

My question is: if I crimp a contact on the ground wire from the gauges and slide that into the negative slot in the low beam connector will that function as a ground? That would do the same thing as bolting the gauges ground to the frame, right?

No reason it shouldn't work.

As long as its not a large current in the ground loop (like the starter ground) you are fine, watch for any jumpy gage behavior in case there is signal noise on the ground/return circuit, it there is then a different ground might be needed

Thanks, guys. Already did it and it seems just fine. I used the city light + for my switched source to my gauges and I used the city light - for the ground. No slicing open the harness to pull a long skinny wire out to bolt to the frame somewhere. Works great. Nice and neat.
The gauges do jump around a lot though but it's from poor contact between the plugs and the gauge ports. These are good gauges for the price but the plugs are crap and they were crap 10 years ago when I first read about them. You'd think the company would have fixed that by now. I guess they bought about 500 million kits for cheap from China and now they have to sell them before they can update. I got ideas though. Wish I could cash in on them somehow. Sure is a lot of work and all for one unit on my bike.