I'm no expert, but I've had to do a lot of things with nothing to work with, mostly had to take nothing & make something out of it.
Theres some RV supply houses, that carry different types of plastic trim that you might could use. Most RV dealerships have these parts catologs & will give them to you free.
On the wiper stuff, if it is the little tube type connectors for the hose, check at an auto parts store for a variety pack of connectors in different sizes. They have straight, T & Y type connectors in a bunch of sizes at Advance or Auto Zone.
The rubber roof, all I've read about repairs, you really need to clean the roof material as perfect as you can & then clean it some more, so the repair tape will stick.
I've had good luck with cleaning & then using the elastomeric type paint sold at Lowes Building supply. Reminds you of real thick Laytex paint, but it drys rubbery like.
Neil