Tom, I believe you could drop your air card and 5g/mos plan and pick up the $30/mos plan instead. You could then tether for internet with your laptop and netbook while at home or wherever plus have the smart phone for internet and the tons of uses while out and about.
Have been amazed at tethering usage of my phone. Mine does not require rooting the phone and once set up, is just a matter of plugging in the mini USB cable between the phone and computer. As soon as the cable goes in, the note on the screen of either my desktop, laptop, or my netbook displays that I am on line. And, the service is always as good or better than with my air card and available wherever there is a tower.
As to a two year contract with the smart phone, I can solve that for you too. I have a huge screen Droid X that I had lost and then found - and in the meantime bought a used Samsung Charge. And it is for sale at a reduced price to my friends or family. Am just about to post it on Amazon. It comes with a desk stand and RV window holder. Makes it nice for the built in GPS or 500plus music tracks I had put on it.
As to the need for a 500mm lens - there is an app you can download that will allow you to use any of your Sony lenses with a Droid X. Trust me on this, Tom.
Actually, have been amazed at the quality of the later smart phone cameras. It is nice to be able to catch a snap shot type pic when out and about w/o my 50D. All of
THESE were taken w/my smartphone.
As to likening your RV to having a sports car . . . ???