I think there are really two issues at play here that cause bicyclists to get hit.
1) Animosity.
2) They simply weren't seen.
For 1, I'm not sure exactly why, but the buttheads of the world seem to reserve their hate for cyclists to the racing crowd. While I have encountered jerks on a road bike, I haven't on a loaded touring bike. This maybe luck I guess, but I imagine a lot of other people notice the same. So for touring, panniers is probably enough.
For 2, I do not think it is a question of width. Its a question of visibility. A few lights placed on both sides of the bike will make you really visible. If someone is going to push it, they are going to do it no matter the width or vehicle. People die trying to pass slow moving cars all the time. The only thing you can do is make sure you are visible imo.
Honestly, if you really are on a tight road and somebody is getting antsy behind you, I just pull over and stop and wave them by. In my younger years no, but anymore a minute or two won't kill me and might save me.