Name changed for this. I, as my user name suggests, am a guide leader. I have been a brown owl with brownies, 7-10 yrs) and a leader with guides (10 - 14) and Senior Section (now 14-25 but in the process of becoming renamed as Rangers with an age of 14-18).
As far as I know, no one in my area has had a trans individual, although there are anacdotal accounts of them else where.
The membership was not asked about these changes from "single sex" to "single gender" although in the past has been asked about admitting boys, when the answer was a resounding "NO".
This issue crops up in various unofficial guiding FB groups and dissent or questioning the mantra of "they are all girls just the same" is closed down. The words "stupid" hysterical and ignorant are used. One said that "terfs can't be feminists". I and others have had their posts removed because we dare to challenge the vocal trans supporters.
For what it's worth, showers and toilets at all the camps and residentials I have been at have always been in separate cubicals, not open plan like the dreadful showers after PE in my old school. There are tough safeguarding rules on adults being alone with girls (you don't basically!) so all that is fine.
I really don't know what I would do if a trans girl turned up - I would be most unhappy about being responsible for taking them away. Teens will be teens, it's hard enough at mixed scout and guide camps with the older groups but the idea of them in the same tents - I would either not go or invest in some single person tents I think!
We are not supposed to inform the other parents or girls, or insist the trans person uses different toilets or sleeping areas.
Oh and a girl who becomes a boy? Has to leave.
It is seemingly impossible to challenge this.