Al was pretty certain that if he had told all that to Severus, Severus would wonder about Al's sanity, motivations, and true identity.
In prior cases when he was required to keep a secret, silence was usually the best idea, so he thought he'd best stick to that.
He raised an eyebrow. "I'll keep quiet until then. Are you certain Mum and Dad will be fine with this?" The idea seemed a bit... odd, but Al supposed the choice of the location couldn't be avoided if one wanted to surprise Uncle Charlie. Al knew that the outside was off limits, but Severus flew him to the Owlery once and there were no repercussions. Perhaps it was all right, after all.
"Um, additionally, would a name tag with a female name of my choice satisfy the drag requirement?"