In July '13, we cleaned our '89 Bigfoot
and applied Zep. We are having the stripes redone this year, so I spent about 20 hours using blow dryer and plastic scraper to remove the old stripes. One PO had painted over the stripes.
This made it more difficult to remove them.
In the first picture you can see where I removed the stripes and then used a spray-on decal remover and/or Goo-Gone to remove any remaining glue/detritus.
We also removed the Zep we applied last year. We used the Zep stripper to remove it. This took one afternoon and we made sure that the stripper was not allowed to dry before rinsing it off. In the second picture, you can see the cleaned trailer on the left and the old Zep on the right. (We had been camping the week prior and had not washed it before removing stripes and old Zep.)
In the last picture, you can see the ghost of the stripes. The shiny part is the original gelcoat and the dull is the oxidized gelcoat where the Zep was removed.
Once the stripes are reapplied, we will be recoating it with the Zep.
I have found that the black streaks are not very difficult to remove. I do use one of the eraser sponges. Do not rub too hard or you will scratch the Zep finish.