I finally got off my duff and washed my trailer today (very proud of myself, lol) but while it cleaned up nicely, I couldn’t scrub off the darkest black “drips” from the window rubber that are stained onto my white Sundowner. I was using a basic car wash shampoo. What product will clean these up? Assuming I’m motivated to get my ladder & humungous hose out again …
Try Mr Clean Magic Eraser, you will need several. I use them on my white Sundowner and they won’t harm the finish.
To get the “hard stuff” Mr. Clean and some elbow grease sound like a good idea. I use the concentrated stuff to clean vinyl/aluminum siding to clean the outside of my trailer.
Use it with the feeder on my power washer. Or just one of those lawn liquid fertilizer dispensers that can be had for a few dollars and attach to the hose. Still may require some elbow grease with a brush on an painters pole.
But sometimes just spraying it on and let work for a bit and rinse off does a good enough job.
I just tried the Magic Eraser and had no more luck than I did with the car wash. I got a PM to get Black Streak Remover from an RV store. I guess I’ll order that.
I used Simple Green Heavy Duty Cleaner and Degreaser (the purple stuff). You will need to wax after.
i would go with the black streak remover that you were pm’ed about. stuff works very well and you can dilute it to make it last, or use undiluted on tough stains. cleaned up a white trailer the other day very nicely.
Just be sure to wear gloves and goggles/glasses.
I had the same issue, I was too lazy to go to the RV store, so I tried Bon Ami, as I already use it to clean my stainless steel kitchen sink. Worked great! I just used a non-scratching sponge. Easy.
I use a product called “Totally Awesome” (I think that’s what it’s called… I have CRS. LOL). Anyway, you get it at the dollar store. It works GREAT!!! I have a white, aluminum Shadow trailer. Gets all those streaks off with ease! It was a tip I got from someone who has a Hawk trailer. 
