We had 50 seats at our wedding - and that included the bridal party !!!. So we were very picky about who we invited....
I would invite the bridesmaids boyf....even though he prob wont know anyone, its your friend, she's in the bridal party....kinda seems right.
When doing the invites address it to the person by name...i.e Sally , we would like to invite you. etc.....if a bridal party wanted partners to attend also, then usually the invite would say : To Sally and partner??? KWIM???

And if anyone approaches you and asks if they can invite their next door neighbour etc i would simply say sorry, cut off is 60.....
Good luck, its an exciting time.