Ten years seems a long time to be buying ahead. As noted above, technology will change dramatically in that time, as will your tastes. I would buy a used 5th that meets your needs now, and take the money you aren't spending on a new full time unit and put it in a special savings fund for your retirement trailer. Then pay cash for it then.
I also agree that your SRW will not be enough for a full timer unit, even if under 37'. I have been looking, and to get a trailer that has quality and holds up to full time, they are much heavier.
Mark