could you wear a tent like that and vampires would be unable to bite you?

I feel like they can't enter your house, as in get their entire body over the threshold. But there's no magical forcefield over the doorway, so if you were standing within arms reach they could grab you. The tent thing is kind of a moot point though, as there's nothing preventing them from attacking a domicile, so they could just tear it or even just poke you with a pointed stick.