On some trips, we pull bikes on a trailer and one or two riders will be riding along side the car.  As the driver of the car/trailer, I would like to be able to use the intercom functionality without putting my helmet on so I can communicate to the riders via intercom.  I've thought of a couple options so far.

1. Buy the earbud clamp with the button mic.  Then I can put my unit in the clamp maybe on the visor, and plug into the aux port in the car, and use the button mic.  Not a bad solution.

2. See if Sena can make it so you can connect to the Sena with a bluetooth device.  In other words, let's say I have a Jabra headset that I use in the car.  It'd be nice if I can hook that up to the Sena.  Then I can talk and listen via the bluetooth headset.  

3.  Buy an entirely new unit like the SPH-10.  But this is expensive, and not sure it's worth buying an entire new setup. 

4.  Use the phone.  Doable, but again, not optimal.

Any other ideas?