Launch / take out point logistics with two paddlers and two vehicles?

I usually launch and recover at the same place.  I fish ponds and lakes most often.  I'm about ready to try some river / stream fishing.  I have a 4 place kayak trailer and a paddling buddy with another car with NO trailer.

Every time I try to figure out what makes the most sense it looks like I'm a ping-pong ball going from launch to take out locations more times than should be necessary.

So what works best for you?  Keep in mind that I don't want to leave the gear unattended at any time. 

Tell your buddy to sell the car and buy a pickup. Seems like the most logical option lol.

Short of that, maybe go in on a rooftop rack for his vehicle.