I looked for my Trillium for at least six months. Closest to home I got was 650 miles away (one way). There just aren't that many in the USA. Good luck with the search!
I have a vintage 1973 13' Trillium I may be selling this summer in order to upgrade to a larger fiberglass trailer. Not yet listed for sale anywhere. Has all the original appliances. I'm in northern New Mexico.