Aero is a far more important than weight on almost all terrain, and at almost all normal riding speeds - air resistance limits your speed far more than any other factors, even when riding relatively slowly. The most aero rim that I know of that is available as rim-only and has an aluminum brake track is the Flo 30: FLO Cycling - FLO 30 Rim It has actually been designed using CFD and wind-tunnel testing, most other deep alu' rims have just been given a triangular form that the designer hopes is more aero but has never actually been tested.

The two downsides of the Flo 30 is that it is quite heavy, 570 grams, but again the aero advantage more than offsets this, and it's not available in an off-center / asymmetric version, but the extra mass in the rim makes it quite easy to build with. The 30 mm depth will give no problems in gusty crosswinds, you have to go up to around 50mm before that starts to be a problem.

I've also built a couple of the new DT Swiss RR 440 asymmetric rims, which IMO are the best option for something lightweight and asymmetric, the tension on the NDS was up to 70% of that on the DS even when building with a 130mm road hub with 11-speed freehub body. However, the rim is much narrower and is less aero than the Flo.