In my opinion, most of the renter's issues will not be related to single sex group or based on age is gender discrimination.
Most of the replies seem to focus on anti discrimination legislation, when the issue to likely to be of a perception of damage to property.
As a cottage renter, my biggest concerns are with people it treating the property with respect and, unfortunately, this is often related to stag or gen parties which are invariably single sex.
The renter's concerns are most likely to be related to a preconception that the dirty campers are moving inside for a stag party (well founded or not, l don't judge).
In order to alleviate those concerns, the original poster may consider what he could do to impact that perception e.g. visit the renter in person to set up the rental, show what type of person you really are, offer to leave a larger deposit as you understand the concern ( offer is appreciated but not usually taken).
Good luck, l hope you get what you're looking for