Welcome to the forum.
Could it be a 1989 model? From what I can remember, the Komfort Trendsetter series started production with the 1989 model year. I could be wrong but that's what I can remember off the top of my head.
They did have a 1989 Trendsetter M-25 which was a 25-foot gas-powered motorhome. I don't see anything listed in the NADA guides for any 1988 Trendsetter models.
The only photo I could find notated of a 1989 Trendsetter M-25 in my files is the link to this one and it probably won't be too much help but hopefully others --former or current owners-- can provide you with detailed photos of both interior and exterior:
Good luck with your project! It should be very rewarding restoring your motorhome.