Ahhhh. Yes, I answered it myself. GetAsDate on my strings works. But, if you happen to read this and know a function that's a bit more elegant than what I'm doing, I'd love to know about it.
s = Tour::StartDate ;
e = Tour::EndDate ;
M = Month ( Client::Birthdate ) ;
D = Day ( Client::Birthdate ) ;
Y = Year ( s ) + ( M < Month ( s ) ) ;
x = Date ( M ; D ; Y )
s ≤ x and x ≤ e
There was an error... now is correct.