I've been in nudist clubs where there is a requirement that men must be fully nude, whereas women needn't be. The logic there is that a woman would typically feel quite uncomfortable in an environment where she were nude and there were clothed males running around. Of course the part about penises being "visible" may be a bit of an exaggeration, but nevertheless consistent with what it means to be nude, if you're a guy.
I've never been to a place where they discriminated to the point that men must be naked whilst women can chose. I have been to ones where everyone had to be naked and others where everyone could chose. On my many visits to naturist venues and beaches I have only seen two erections. I one case (judging by tan lines) the man was new to nudism and rushed into the sea to hide his embarrassment. The other time was as we arrived for a nude feast. Those who arrived clothed stripped off on arrival. It included one couple. Immediately after a particularly attractive lady arrived and undressed. The man suffered an immediate erection which we all ignored. Having said that there are places like the far beach at Cap d'Agde where erections, and sexual activity, are not uncommon.
I get them too, usually my wife discreetly uhhh handles it so it is not an ongoing problem. The key word is discreetly. There was a guy next to us last time who had the hard high one going for a long time and was not discreet. He was very proud of the wee thing. It happens, but be discreet
Last sumer my wife went to a club with me her first time she stayed dressed we were there for a hour or so and I asked her if she liked it she said yes but was surprised she did not see any men walking around with erections I told her that doesn't happen much but would it bother her if it did she said no words from a non nudists I know some woman might get up set but
An erection is a normal, physiological response of a healthy body. While it does suggest sexual interest in gay or straight men it's nothing to be ashamed of and it's part of being nude. Sport it with pride. It's not different than hard, erect nipples on her breasts. i may have already commented on this.
Another Moronic post to give nudism a bad name and deter genuine nudists from joining this site.