Heads up, all. I've discovered a pretty serious, but easily avoidable, issue. If you try to save and leave the game when any Unloaded Items exist in the world (on the ground, in a chest, in inventory), the game may fail to save and a backup will be loaded of your last save the next time you load the character. Be very careful about disabling mods while this is active, so that you don't lose any progress. As long as you completely dispose of any Unloaded Items before saving and exiting, there should be no problems.
I've talked with Blue about the issue, and it seems to be a tModLoader bug. Nothing I've done with the Save/Load code, short of disabling custom Save/Load entirely, fixes the issue. Hopefully, an upcoming tModLoader update will fix this.