I think you may be a little confused. If I recall correctly, Aquila makes a Concert set for 5ths tuning, but it is CGDA, not GDAE, which would be very low (hope you're not trying to tune up an octave).
String sets are very tricky in 5ths. Even with steel strings, there is a lot of 1st string breakage. With classical strings it is even worse.
As far as gauges, remember that compared to the pure steel, treble material gauges mean next to nothing. The gauge of a very dense material like flourocarbon is a lot different than what you would need with a softer material like nylgut.
We make one set only for 5ths tuning. Since the spacing between notes is a step wider, it means that the whole range of strings is 4 notes wider. This makes the 4th string somewhat heavy and the 1st string pretty thin. We have found only one way to do it well. Our set gives a 4th string that is not ridiculously fat and squeaky, paired with a 1st string that is strong enough to not break.
You simply have to take this set at whatever tuning it works out to on your instrument. It gives CGDA (key of C, by the way) on a 17" scale (standard Tenor Uke). A set-up with two wound strings will be better on a Tenor than a Concert to begin with. While I've always liked Aquila strings, I think they missed the boat on this one.