I noticed that the seatpost for the stoker position on the rental Burley was all the way in, but the Cannondale geometry should allow for more room to put the Thudbuster seatpost. Wine and Tandem sounds like the perfect weekend. I may have to try it, but Texas it's not up to par with Ca. when it comes to wine.
Thank y'all for your advice, it has been very helpful. I will certainly tap into your knowledge in the future.