I believe that couples should practice being naked together especially when they are first married. The body is not bad, but it is private.
Therefore part of intimacy is being together, being able to be accepted completely for who you are. Your body is part of intimacy. When two people share their bodies together and are able to be "naked and unashamed" they share a bond. They share a part of themselves that they don't share with other people. Being naked is a natural part of a marriage relationship.
I have been to nude beaches several times, and it's not really about the other people who are there. Rather, it's safer or less likely that you will get into trouble by being around likeminded people. That's why you go to a nude beach instead of off somewhere by yourself where you might get arrested.
The nude beach is all about being free, feeling and experiencing nature. I have lied on the beach and felt the sun, the breeze, and the soft spray of water from the crashing waves. It is beautiful. I love it.
Did I have an erection? Sure. Lots of guys have erections at the nude beach, but out of courtesy for others they just ignore it. Sometimes I turned over onto my stomach until it went away or just lied on my back and pretended nothing was happening.
However, you should not have an erection on purpose. The nude beach is not about sex. And, certainly there is no masturbation or sex allowed. That will get you into trouble and jeopardize the beach for everyone else. The police do not tolerate public sex acts.
Your body is beautiful. You and your spouse should enjoy one another. Be kind and loving, natural and healthy.
I've heard that too, about being kicked out if you get an erection. I don't know for sure though. I've been in an few nude situation, nothing sexual. It was actually difficult to think of anything too erotic at the time and I couldn't imagine being able to get erect. I guess, if you were sitting around staring and good looking people of the opposite sex, it might be different.
I have never had any experience with this personally, but I have a close friend that has been to nude beaches several times, and he says that it is so natural that you really don't get turned on by it.