I just had a quick look, and this seems to doable pretty easily. If you look in the panel.xml file for your aircraft (eg, in this case, Packages/Official/OneStore/asobo-aircraft-bonanza-g36/SimObjects/Airplanes/Asobo_Bonanza_G36/panel/panel.xml in your FS install directory) you’ll find a line that says
Either change that to False, or just delete the line entirely, and you should lose synthetic vision. This is also something that could be controlled through the menu system, but I have no idea where that would be and I don’t have a G1000 simulator, so someone would need to show me at some point.
I haven’t explored these devices enough yet to know if that kind of logic is contained in the displays or if it’s (like I suspect) a deeper part of the aircraft that would take more work to fix.