Hi,
On the pics you posted above, you have a project on your hands. It does not look good. If you only have one day to work on the camper, I suggest you cover it with a tarp. Then, with bungee cords, strap it down well so the wind does not get under it. Then, create a plan on how to deal with the work.
You can try to get the old stuff off or see what process works so when you come back to getting time to work on the camper; you know your method will work getting off "all" the old patch jobs done wrong. Then, cover the camper back up.
To get the tar and other possible stuff off, I suggest using a heat gun and a stiff metal blade scraper with all the blade end edges dulled up so as not to scratch the roof. See if the heat will soften it enough to scrap the large part of it off. Keep the heat gun moving so as not to burn while standing still. If you have no heat gun, a hair dryer can work in a pinch for a short time, although you damage the hair dryer if you use it for a long time, so make sure it is not the only good one you have for the house. You only need a simple 1,400 to 1,500-watt heat gun; one or two speeds are good enough.
Once you get the major stuff off, try the chemicals to get the rest of the fine stuff off. I would start with mineral spirits on a rag, wipe it on, let it stay for a minute or two, then scrape, rub, and rub to see if it will cut the little traces left over. I have yet to try the Xylene you mention if it will strip the paint. I know mineral spirits will not strip the paint. Mineral spirits (MS) will leave a film that needs to be removed after cleaning with it. I use Naphtha, a high-flash cleaner; it eliminates the MS film and evaporates quickly, leaving almost no residue. Denatured alcohol will also remove the MS film; it just has very little cleaning action compared to the mineral spirits and Naphtha.
If you have silicone caulk up there, scrape it down as far as you can. Then try Goo Gone or another silicone remover to soften the little traces left, and scrape and wipe some more. It won't be easy getting silicones off on the metal that has a pebbled metal surface.
I would recommend you "do not" start the Henry Tropicool process at this starting point. There is too much to learn about checking the bond to the surface, storing the product so it does not harden in the gallon can after you open it several days later, and much more learning. You should only consider the Tropi-cool application once the entire roof is repaired and cleaned, and you know you do not have to lift the roof to fix water-damaged wood under it. Yes, you can repair broken vents on a Tropi-cool coated roof, but that is not the same as opening up a roof seam the width of the camper.
If you can clean the front seam down to the metal, use Dicor's self-leveling lap sealant on the seams or other joints on the roof, vents, etc.
https://dicorproducts.com/product/self-leveling-lap-sealants/.
It is sold in many RV dealers or online. It comes from a standard-size caulk tube and will bond to "clean" metal roofs. You have to get the surface clean. It will not bond to dirt, oil film, tar, silicone, etc. Using the Dicor now will stop leaks once cured. It is rated for RV road travel, and you can more easily remove it if the seam has to be done to repair the camper. The Dicro will buy you time to do all the seams and open one tube at a time. Also, it is what is used on new campers from the factory. While the Dicor caulk needs constant maintenance attention annually, if properly applied, there are very few cracks in the caulk in the first three years. As time passes, more cracks will come that must be cleaned and touched up. But doing the Dicor now gives you a few years and little time to apply the Dicor. And you can do it in stages.
Later, when you know the roof is all cleaned and prepped, any damage is repaired; only then, if you want to apply the Tropi-cool, will it bond to clean cured Dicro lap sealant and a properly prepped roof.
I hope this helps.
John
