In that case, definitely take a deep breath and venture inside the pub. Go stand at the bar and start chatting with the bartender. There was a friendly gal working there when I went, same one as in the photo on the web site I linked to. Even if the person behind the bar is a guy, it is usually quite safe to chat with them since it is part of their job description.

Once people heard my Canadian accent, I got the inevitable question about where I'm from and what I'm doing here so far away from Canada. The conversation just naturally evolved from that, and soon I was amiably speaking with a few of the regulars who had no ulterior motive other than enjoying a drink and a chat with a newcomer. Really friendly, and no trouble at all.
If you are really that shy, then bring along a prop like a tourist guide book or a map of Backnang and the area. Someone is bound to take interest. If you go in the afternoon then you might run into a few older guys who might even tell you all sorts of interesting trivia about the area and local places of interest to visit. I love using pubs as "tourist info bureaus" when I'm off playing tourist on my own without my husband.
Or else go with your husband the first time. Then you'll find it much easier to go a second time alone since you'll have met the bartender at least and won't feel like such a stranger. I wouldn't place too much importance on the "hostile looks" you feel you've been getting. Heck, there's a whole thread here about it:
Staring Germans, why do they do it so?, Stares seem to be an annoying national trait here. With over 300 posts, you can tell that it really is a German thing and nothing to be taken personally.
So ignore the stares, go in the pub, order a beer or cider or coke, and say hello to the bartender. If you absolutely hate it there, then you can just leave after the one drink and no harm done. But you'll probably end up spending a few hours having a nice chat, meeting a few of the locals and making new friends. Can't be more difficult than arranging a "blind date" (or simple meeting) with someone here on TT, can it?