Acceptable Open-Water Strokes?

So, I've signed up for a couple of open-water swims this summer (the total will be 3, once signups open for the 3rd one), and I'm very excited and very nervous, as I haven't done a "race" with other humans in ... like 20-odd years. I've been diligently working at my endurance and speed for several years after that long hiatus, but the kicker is that my freestyle/front crawl is still quite pear-shaped (I can do 100yds at a steady, not fast pace, and 200yds in a pull-set), and breaststroke is my pick for any kind of distance. Last year I spent a lot of time in the local lake tooling around the periphery of the "adult only" area (About 6 rounds equals 1 mile) making reasonable time, and my warm-up in the pool is a nice 500yd BS. I'm not breaking the lifeguard test requirement of 500yd in 'm not taking 20 minutes like I did when I first got back to swimming either. Long story short, while I've signed up for 1/2 miles in all of these races (and might even be middle-of-the-pack, judging by other folks' times in past years), I just don't think my freestyle will be up to it. Is it ok to swim breaststroke, as long as I keep knees and feet out of other people's way? I have seen nothing on the race websites forbidding it or requiring a specific stroke, but I wasn't sure if there was a sort of gentlemen's/women's agreement that you just don't do that. (also, any other advice for my first time in 20ish years "competing" with a bunch of folks would be appreciated. One is a lake swim in early June, two are ocean swims in relatively calm coves later in the summer. They're all in Massachusetts.)