I'd say that just car wash soap and water are the best things to use.
I'd avoid any kind of chemical maintaner/protectant/treatment/conditioner for rubber seals.
Everything I've ever used, a wide varity of products, has always, always resulted in a breakdown of the rubber, or at least the surface, within years. I've completely stopped using any of it after noticing it accelerates the cracking of the sidewalls on tires, and caused quite a few hard plastic components to crack and disintegrate.
These days I just use carwash soap and water and haven't had problems. If I need to get rid of greasy film on a rubber seal or there is something that carwash doesn't remove, I use Dawn dish detergent since it degreases really well.
The other advice I'd give would be to park in the shade whenever possible. Besides chemicals, most of the breakdown of rubber parts and seals is from UV rays in sunlight, so the less UV the seals are exposed to, the longer they will last.