Thanks guys. The question came up while we were perusing Trailer Life's big directory last night looking at length restrictions in campgrounds. I decided to read the material in the front of the book explaining the abreviations, etc when I came across this chart showing the towing laws in all of the states. I was shocked to see that many states had a maximum trailer length of 40' which is a foot or so shorter than the length of the trailer that we are considering (ouch!). I wondered if a fifth wheel trailer was measured differently since part of it overlapped the tow vehicle.
After I posted this question, I called several state DOT's. The only definitive answer I got was from Florida. They said that as long as I did not exceed the maximum combined length I would be OK. Theirs is 65' so we come in about 7 feet shy of that. Seems strange that almost all of the major manufacturers make trailers that are longer than "legal". However, the guy I talked with from Florida said as long as it wasn't a commercial vehicle, we didn't have to worry. Some states such as Georgia and Colorado do not state a maximum trailer length; only a maximum combined length. Oh well, I guess we'll see...
Thanks,