Where I live I don't have to go anywhere to get my trailer covered, pounded or sand blasted by dirt - it's the nature of the land.
I clean all the seals with denatured alcohol and let it dry. I then use a cloth with Aerospace 303 on it and rub the seals down. After it has absorbed for a bit (by the time I get from one end to the other applying it) I go back over it and dry off any excess with a dry cloth making sure it is completely dry. It keeps the seals clean, soft and flexible. It has UV blockers that are supposed to help protect the seals.
Whatever you do don't just skip cleaning and treating them. Just helped a newbie a couple of days ago getting set up. Bought a '17 (memory) Cougar Xlite from a family member and brought it here. As I went over it with him (slides were giving him trouble too) I looked at the 3 slides. Every one of them had slit, torn and pulled out seals - every slide. Looked like they had never had any maintenance at all. Reinforced to me that although sometimes it feels like a real pain worse things will happen if I don't do it.