La Monte,
If I remember correctly, the sealant on the trim strips on the "waist line" of our 01 Contessa Naples was simply to keep water out and seal the edges against the wall of the coach. Lexel or a silicone is sufficient. The factory used a silicone type sealant. While (IMHO) Lexel is a better sealant, silicone is easier to work with, especially on areas such as these that are visible. In any case I would not use a permanent type sealant as you or a service center may need to remove the strips in the future.
Steve