Right Mary ...
In the late 80s to the late 90s, Casita
(like the entire RV industry) experimented with several straight multi-line graphics ... using a different number, location and width of graphic straight pin-stripes.
Some of the changes were made mid-year, which pretty much makes it impossible to tell exact year ... just eras
The swirling graphics appeared mid-model-year 1999 (if my memory serves me right), to update the look of the trailer, as did most of the RV industry.
So I guess you could get a ballpark age from that change, since it's the most obvious change.
And yes, long time friend Carol C is right. I once bought a new Casita
just because my wife thought the graphics were prettier. (So I'm not sure I view the graphics as a good thing :) )