Seeking th perfect Couples Trailer - just me and my wife ...

It sound like you know what you want. I would strongly encourage you to stay with the lighter units, say around 3,200 pounds or less. You tow vehicle will be much happier which makes for easier travelling. The newer RVs have aluminum frames and fiberglass shells saving a lot of weight. The tradeoffs with lighter units are no big deal if it is just the two of you.