I agree with TT over B. You already have a good (I assume it's good!) tow vehicle that you know well. With a used B, you have a whole 'nother drive train to maintain, and you don't know how it was cared for beforehand. Plus I think the TT will feel a little more spacious than the B, and you still can throw stuff in the back of the pickup (tons of space!).
Casita or Scamp will get you a couple more mpg's than the RPod, and the molded fiberglass trailers hold their resale value much better. If you're buying new, also take a look at
Parkliner (built in NC) and
Li'l Snoozy (of SC). All of the molded-body trailers are sold factory direct (but internal components are common, with their own warranties, and are easily serviceable anywhere).