Dual Batteries Charging Question

So, here's my situation.  I have a folding solar panel that has SAE-style plugs.  I have purchased a couple of panel-mount plugs like pictured below to play around with, and would like to add one to the battery box.  My problem is the pod has dual batteries in separate boxes on the tongue, and the leads on the plug aren't long enough to reach both.  Can I get away with mounting the plug and wiring it to one of the two batteries?  Or is the only acceptable way to charge dual batteries to wire to opposite ends of the 'bank'?

Originally posted by CharlieM OR connect to one battery and don't worry about it. The relatively low currents available from the solar array won't make much difference.

This is exactly what I was wondering about.  I could easily extend the connector to the other battery, but I'm not sure that I need to.