Been there, just did that, with great results, with little effort. I just posted a thread about a week or so ago (Fiber Glass rejuvenation)and did some past post research on the problem. The biggest responses were for 2 products, both by the same manufacturer. The first was produced for and carried by Lowes called " Red Max Pro #3" and the second carried by Home Depot "Zep". Both are about $16 a gallon. The biggest part and most important part of the job is the initial prep and cleaning. I labored for about a year with 3M's fiberglass rejuvenator and wax with limited hard earned success, then I found Red Max thanks to iRV2.
On the initial prep you will need two additional reasonably priced products, "Bar Keepers Friend"
Bar Keepers Friend | Cleaning Products | Household Cleaning Supplies and TSP Trisodium Phosphate by Savoran, both also available at Lowes. Rubber gloves, 3 M scrath pads and a good fresh water rinse source (Garden Hose).
My Winnie has fiber glass sides also and they also needed cleaned and treated, I not sure if you have the same. In any case the roof will have to be cleaned and preped for the Red Max coating and the streaking down the sides can be cleaned with the TSP.
The roof cleaning and initial prep is done with the TSP solution and tough stains,pine pitch, bird DoDo etc is removed with the 3 M pads and Bar Keepers Friend and a good rinse.
After a good dryout, because the Red Max doesn't like water during initial application you'll be ready for the Red Max application.
To apply the Red Max I'd recommend you have a new or clean plastic container to pour the Red Max solution into similar to what's used for paint rollers. Rubber gloves, and clean or new micro fiber cloths. On the roof and large areas you need to work controllable sections or areas. Rubber gloves on (Which is the hardest part of the job)Pour a useable amount into the pan, fold the micro fiber cloth in quarters into a controllable applicator and immerse it into the Red Max Solution and squeeze out the excess, you don't want it dripping wet, but just similar to damp wipping. Apply the Red Max in overlapping stokes over the work area and wait for it to dry which takes about 20-30 min depending on temp and thickness of application, don't puddle it. Recoat the area again and let dry. The Red Max instructions say 3 coats but but I've found it takes about 5 to really see a good shine. I assume it's because I apply thinner coats with the micro fiber rather than a mop. When you see the final result you'll be amazed, after about 8 months you'll have to recoat with 2-3 coats to rejuvenate and reseal, however your streaking will be gone forever.
Another tip; Make sure the surface is clean, because whatever you seal under the coating will be there forever.
My total RV, Top and sides took 2 days, but I was extremely pleased with the results. The Red Max also rejuvenated the fading decals on the sides and window trim and dull rear view mirrors.
I am not a Red Max sales Rep, nor do I work for Lowes. However I was totally pleased with the results. The biggest problem I encountered was trying to buy the product. Lowe's had Red Max 1,2,4 and 5 but no 3. This is a floor care product and all the Lowes don't carry it. You just have to get into the right Lowes, some still have it on the floor. It's ITEM # 216595. I did find after several weeks a Lowes that could get it for me so I got 3 gallons. It took only 1 gallon top and sides for the initial application, but I got 2 more for future use.
A bit windy on my reply, but that's only because I was so happy with the result. I'm sure you will get several posts on your problem, hope mine will help a little, If you need additional just use the query box on the top of this irv2 page and type in Red Max Pro and search.