Thanks for all the help so far. I'm replying on my phone, so I'll put all my responses in one post.
I do not plan to buy a truck or van until after I have chosen the trailer. I would also prefer to get an over-powered truck so I will have more leeway in the future. Yes, diesel is the way to go, both for power and for the possibility of using biodiesel.
When I first buy the trailer, I will either get someone to move it to its first home for me or I will rent a Home Depot truck and move it myself. I will then have a year or so to find an appropriate truck. Considering my budget, it will have to be used. I don't care if it is pretty as long as it can haul the load.
That said, I don't want to end up buying a trailer that can only be pulled by a truck I will never be able to afford or that will use up so much gas between moves that I could have just paid for someone to move the trailer.
When I said I could go slowly and carefully, I didn't mean 20 mph on the freeway. And I didn't mean I would be using an underpowered truck. I just know that some people have complained about the difference in stability between a hitch-mount and a 5er. I can deal with that slightly decreased stability for a once in a blue moon move. I am also pretty darn sure the gub'ment (as idiotic as they can be sometimes) wouldn't have allowed manufacturers to make 30 foot hitch-mount trailers if they were unsafe at minimum highway speeds when pulled by an adequate truck.
My problem is that I still have absolutely no idea of how much some of these trailers weigh. Without that, I can't start making any kind of assessment as to how much truck I should plan to get. I'm not looking for precise values. Just general guestimates. Does an average 30 footer, with all the standard trimmings, usually weigh in at 5,000 pounds? Or is it closer to 10,000? How much would a 20 foot Airstream generally weigh? All I want is some ballparks. If anyone knows of any resources that could give me the info I want, I would appreciate that too. Yes, Iknow Google is my friend. But sometimes google can be a little too friendly and give you way too much random information. I would rather trust some guesses from old hands than a bunch of precise sounding but possibly random or made up numbers from the intertubes. (Yes, Iknow, Cheap RV Living is on the intertubes too.)
Thanks,
Grant