Sure but in small GA planes you're not likely to be travelling so far that the magnetic declination is significantly different so just keep it in mind each time you reset the DI. Or if you are travelling long distance you could make a note of it along your planned route, or your GPS app could let you know.
My point was that this shouldn't require any instrument upgrades to the GA fleet
My point was that this shouldn't require any instrument upgrades to the GA fleet