Oscarthecat, thanks for your service. My mom was a Navy nurse in WWII, stationed at Pearl Harbor for a while (after the war started, not in Dec. 1941).
Spend as much time looking at floor plans as you can. When you aren't looking at your computer screen, go visit trailers. It won't take you long to figure out what floor plans will suit you.
You say that you're going to start out with the trailer parked, and then in a few years go traveling. With that in mind, you may want to consider hiring someone to haul your coach to where it will be parked at first, and not worry about whether or not your daily driver will be able to haul it. When you get to the point where you want to use the wheels under your house, you can trade vehicles for one that will be able to tow the trailer.
Visiting PPL in Houston has already been suggested, and I'd second that. I've not visited there, but we're talking about it for this summer. From the pictures I've seen, it looks like all of their 5'ers are parked in one area, travel trailers in another, and so on. After you've visited a dozen or so 5'ers, take a minute to see how your legs feel. Then go through a few Airstreams.
If you are going to have a home base (a permanent place that you will return to at the end of a trip), you can probably have a storage shed for the things you don't need now, but will want later on. That also will cut down on the weight that you are hauling around when you do decide to travel.
Mercury Mountaineer towing mpg 181(both sold)
1993 Foretravel U300 40'