I have had good luck with securing the Kayaks side by side and doing it that way.
That's what I did this past weekend, when my girlfriend got tired of paddling the KeoWee2. Put my fenders out, lashed the two boats together and pedaled both of us along. In calm water, I could barely tell there was "dead weight" (don't let her know I called her that!) strapped to my Outback, and the rudder was still very responsive. Plus, conversation is a lot easier than it would be with her at the end of a tow rope. (I suppose that's an advantage!)