Thanks to everyone for their input. jrichards, I may be overthinking this whole thing; however, after talking to so many sales people and reading SO many blogs on proper towing, I'm trying to un-confuse myself. One salesman told me that as long as our trailer weight didn't exceed our tow vehicle weight, we were fine. Another tried to tell me that adding a WDH would give us more towing capability (see what I mean ... ). We don't plan on using this TT to live in but, rather, as a supplement to some extended traveling (I still like "hotel camping" ... ). Thus, we don't plan on hauling a ton of "stuff", but we still want to be comfortable ... and safe.
Taking the given numbers at face value, it appears that towing a 5400 lb trailer (max) may be okay; however, per some of the postings I've read, if we have 6600 lbs GVWR - 5500 curb wt (weighed on a scale) - 600 lbs passengers/gas/WDH, we get a real tongue wt of 500 lbs -- much less than our 690 lb book rating.
Taking the new tongue weight and using the 15% ratio which I keep reading about, then the maximum trailer wt should be 500 lbs (tongue)/ .15 = 3,330 lbs maximum trailer weight. If you use a 10% ratio, then it becomes: Maximum Trailer Weight = 500 lbs / .10 = 5,000 lbs. which means the trailer we're looking at is over our limit by 400 lbs.
I'm just wondering whether I'm forgetting something in this equation or if my figures are wrong. Thanks.
