I need an opinion on how other couples handle this. We knew and accepted (I thought) that we belonged to opposite parties. We also agreed it would be best to not have political signs in our yard at election time. However he is much more expressive than I with regard to magnets, bumper stickers, etc. It's stressful having them in my face all the time. Plus I don't want to drive or ride in a car with an opposing view advertised. It's awkward when someone comes up and says something like "I like your bumper sticker" when I don't approve of the person. I guess I feel like he is speaking for me and I find that disrespectful.
Lately I have been more and more unhappy about this. I just want a peaceful home where I am not being judged.

But I don't know how to broach the subject or if I even should. I know he has the right to express his opinion too and to do what he wants with his own property. I just feel like there's no good answer. If he agrees to not do this, would it just cause resentment and make things worse? I'm not about to respond by doing the same. It's not my thing to put stuff like that all over my car or house and if I did it would be out of spite.

Am I overreacting? I'm not going to say who's the D and who's the R because it's irrelevant and I don't want any specific political opinions.

I would use the policy of joint agreement. It should apply in everything you do. The Policy of Joint Agreement