The Q/A below says to me that joint Troop (boy Troop & girl Troop) activities are allowed, but that a Leader may not bring their son/daugther to an opposite sex Troop activity without their child’s unit participating. As has been stated above, tag-a-longs. I interpret this to be a concern about relying upon the hosting unit providing the proper adult leadership requirements. If I bring my daughter to my son’s Troop campout, there may not be a female registered adult present.
Q. Can Scouts BSA girl and boy troops share a campsite?
A. Yes, if the campsite’s layout and amenities meet all the requirements of Scouting’s Barriers to Abuse, including privacy and separate accommodations. Each unit must also meet supervision requirements.
Also, the BSA purposely kept the Troops separate so that the youth could grow and learn with their own gender. Girls and Boys both mature at different rates and in different ways. They interact with each other differently. I am a Cubmaster of a Family Pack and have seen girls in their AOL year start to be less interested because they think that in the Troop they will have to integrate with the boys. We of course educate them that they will be in a Troop with just girls and will plan their own activities. I am not a fan of linked Troops as I believe there have been instances where the much smaller girl Troop was having to acquiesce to whatever the boys decide to do because the girls have less of a vote/voice. The opposite might happen if the boy Troop was smaller. I was also the Scoutmaster of a very small girls Troop for nearly 2 years and they still need to be able to chart their own path and be proud of their own unit. I am sure that some have made it work with linked Troops, but as the girl Troops grow I would expect they will disengage from the boy Troop to be autonomous.
For what it’s worth, that is my opinion on this subject.