Hmm... If you were tenting I could see a concern. You have RVs. You have A/C and cold drinks, and ice cream. Yum! Can the kids play board games inside? The pool is in the sun? Go figure. And it will still cool you off and be fun for the kids. Just make sure to use sun screen! Are there museums or other indoor attractions within a reasonable driving distance? We've even gone the movies on hot days. Fires are great but you can still and have fun. Due to fire bans we've had plenty of camping trips "sans fire". Put a few coals in the fire pit to roast marshmallows. Otherwise just enjoy the conversation and the cold drinks.
Don't cancel! Get creative. It might be even more fun for everyone because you'll end up doing things you might not normally do.