Every 5-7 years Douglas Firs in the Pacific Northwest have bumper crops of cones that drip sap everywhere. During those years, huge amounts of pollen also are released that form black spots on the trailer roof. I could avoid this problem, but clear cutting my yard and the neighbor's yards would not go over well. I am reluctant to put a cover on the trailer during sap fall, so I remove the sap every week or so.
Drops of sap are scraped off with a plastic paint scraper (which will not scratch the gelcoat). Then I use a microfibre towel soaked in orange goo gone to remove the spots where sap has dripped. After sap removal, I then spray the area with Meguiar's QuikWax and buff with a clean microfibre towel. This is pretty labor intensive during the year's with heavy cone production, but not much issue in most years.
Having a good ladder is a must. I use a little giant mega max, which is stable and easy to set up in close proximity to the trailer without leaning it against the trailer. It is easy to set up the side alongside the trailer one notch lower so the ladder is perpendicular on the trailer side and climb up and over to the trailer side (never putting my feet on the top two rungs) so I can lean over the roof to reach all of the way to the center of the trailer. This method leaves me with a completely stable platform when cleaning the roof.
The pollen (and leaves/needles in the fall) combine with fall rains to nourish algae, which creates very difficult to remove black stains (very solvent resistant). I deal with this by purchasing bug sponges (or pads) that are a very open cell, stiff sponge. They are non-scratch and remove the black stains completely in most cases. If a small stain remains, a quick hand buff with Meguiar's ultimate compound, followed by a buff with Meguiar's ultimate polish, removing the rest of the stain. I finish off with a treatment of Meguiar's QuickWax. I also do a spring and fall cleaning by washing with turtle wax Zip Wax car wash. I do the fall cleaning at the end of my main camping season (when I winterize the trailer) and cover the trailer with a good quality cover (I live in Seattle, which has pretty wet winters). I do occasionally use the trailer to winter camp, but keep the trailer winterized and dry camp. Since our summers are fairly mild and my trailer parked in a shady area, it is easy to maintain the gel coat by a quick wash with Zip Wax after trips. I have no reason to cover the trailer during the summer season. The bug sponge is great for removing insects that collect on the front of the trailer on trips.
Drops of sap are scraped off with a plastic paint scraper (which will not scratch the gelcoat). Then I use a microfibre towel soaked in orange goo gone to remove the spots where sap has dripped. After sap removal, I then spray the area with Meguiar's QuikWax and buff with a clean microfibre towel. This is pretty labor intensive during the year's with heavy cone production, but not much issue in most years.
Having a good ladder is a must. I use a little giant mega max, which is stable and easy to set up in close proximity to the trailer without leaning it against the trailer. It is easy to set up the side alongside the trailer one notch lower so the ladder is perpendicular on the trailer side and climb up and over to the trailer side (never putting my feet on the top two rungs) so I can lean over the roof to reach all of the way to the center of the trailer. This method leaves me with a completely stable platform when cleaning the roof.
The pollen (and leaves/needles in the fall) combine with fall rains to nourish algae, which creates very difficult to remove black stains (very solvent resistant). I deal with this by purchasing bug sponges (or pads) that are a very open cell, stiff sponge. They are non-scratch and remove the black stains completely in most cases. If a small stain remains, a quick hand buff with Meguiar's ultimate compound, followed by a buff with Meguiar's ultimate polish, removing the rest of the stain. I finish off with a treatment of Meguiar's QuickWax. I also do a spring and fall cleaning by washing with turtle wax Zip Wax car wash. I do the fall cleaning at the end of my main camping season (when I winterize the trailer) and cover the trailer with a good quality cover (I live in Seattle, which has pretty wet winters). I do occasionally use the trailer to winter camp, but keep the trailer winterized and dry camp. Since our summers are fairly mild and my trailer parked in a shady area, it is easy to maintain the gel coat by a quick wash with Zip Wax after trips. I have no reason to cover the trailer during the summer season. The bug sponge is great for removing insects that collect on the front of the trailer on trips.
As for many topics there's cover fans and no cover fans. 
