You could build up the LX hubs with Open Pro rims. This would be reasonably light and accept 23-28mm tyres.
If you want to get more aerodynamic, think about width as well as hight . Some Spinnachi style mini clip-on bars or small aerobars would bring your arms in and eliminate the parachute effect.
Is is possible to set roadbars higher than a race bike. This would give you plenty of alt handholds and maintain your more upright stance.